MIS 140 Midterm Review Part 1

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existence-dependent

A property of an entity whose existence depends on one or more other entities. In an existence-dependent environment, the existence-independent table must be created and loaded first because the existence-dependent key cannot reference a table that does not yet exist

software independence

A property of any model or application that does not depend on the software used to implement it.

When sending four bits at a time using frequency modulation, the number of different frequency levels that would be needed would be _______.

16?

How many bits are required to sample an incoming signal 4000 times per second using 64 different amplitude levels?

6 bits

Media access control: a. is not very important in point-to-point with full duplex configuration b. is not very important in local area networks c. is not very important in a point-to-point with a half duplex configuration d. is not very important in a multipoint configuration e. does not control when computers transmit

ARQ means that: a. a receiver that detects an error in a message simply asks the sender to retransmit the message until it is received without error b. the common carrier Automatically Returns Queries to the subscriber upon receipt of such queries c. a sender is using a data link protocol called Asynchronous Repeating reQuest d. a fiber optic cable meets the American Registered Quality, a certification standard for use in high-quality data communication transmission lines e. a sender is using a parity scheme called Array Resource Quality

The two sublayers of the data link layer consist of the media access control sublayer and the________ . a. logical link control sublayer b. network control sublayer c. session sublayer d. physical sublayer e. transport sublayer

Using parity, the probability for detecting an error, given that one has occurred, is: a. about 50% for either even or odd parity b. about 70% for even parity and 30% for odd parity c. about 30% for even parity and 70% for odd parity d. about 0% for either even or odd parity e. about 100% for either even or odd parity

Which of the following is true about the data link protocol, PPP? a. it is commonly used in WANs b. it is a bit-oriented protocol c. it uses block check characters for error detection d. it was developed in the 1960s e. it uses parity bits for error detection

Which of the following is way to reduce or eliminate crosstalk on a circuit, a. changing multiplexing techniques b. adding repeaters or amplifiers to a circuit c. reducing the length of the cable d. adding fluorescent lights e. shorting a circuit

Which of the following is way to reduce or eliminate crosstalk on a circuit? a. physically separating the cables from other communication cables b. adding repeaters or amplifiers to a circuit c. reducing the length of the cable d. adding fluorescent lights e. shorting a circuit

Which of the following media is least susceptible to noise? a. fiber optic cable b. coaxial cable c. twisted pair d. unshielded twisted pair e. shielded twisted pair

Harmonic distortion can be prevented by a. tuning equipment b. moving wires c. increasing guardbands d. increasing signal strength e. using a high-speed circuit

If a signal with a frequency of 500 MHz combines with a another signal of 1500 MHz and they form a new signal of 2000 MHz; this is an example of: a. intermodulation noise b. attenuation c. echo d. jitter e. harmonic distortion

In a _________ , more than one data bit is changed by the error-causing condition. a. burst error b. data rate shift c. Trellis-coded modulation d. uniform distribution e. amplitude key shift

In communication protocols, _________ are used to convey the user's meaning. a. information bits b. overhead bits c. stop bits d. start bits e. flag bits

With __________ ARQ, the sender immediately sends the next message or packet of data. a. continuous b. immediate c. open window d. stop-and-wait e. halt and be recognized (HBR)

With contention: a. computers wait until the circuit is free before they send data b. the server or front end processor works consecutively through a list of clients to determine who should have access to the media c. the front end processor must wait for a response from the polled client or terminal d. one computer starts the poll and passes it to the next computer on the multipoint circuit e. there is never a chance for "collision," or two computers trying to send data at the same time

_____________ is an effective way to prevent impulse noise, cross talk, and intermodulation noise. a. Shielding wires b. Adding fluorescent lights c. Adding repeaters to a circuit d. Adding amplifiers to a circuit e. Shorting a circuit

______________ controls errors by detecting and correcting them at the receiving end without retransmission of the original message. a. Hamming code b. Huffman encoding c. Front end processing d. Wave division multiplexing e. Hub polling

entity cluster

A "virtual" entity type used to represent multiple entities and relationships in the ERD. An entity cluster is formed by combining multiple interrelated entities into a single abstract entity object. An entity cluster is considered "virtual" or "abstract" in the sense that it is not actually an entity in the final ERD.

centralized database

A database located at a single site

operational database

A database that is designed primarily to support a company's day-to-day operations.

performance tuning

A database that is designed primarily to support a company's day-to-day operations.

multiuser database

A database that supports multiple concurrent users.

single-user database

A database that supports only one user at a time.

system catalog

A detailed system data dictionary that describes all objects in a database.

relational diagram

A graphical representation of a relational database's entities, the attributes within those entities, and the relationships among those entities.

Explain how instant messaging works.

An instant messaging (client) communicates with an IM server application. Once a user is online, the server application can monitor connections so that multiple pre-identified clients can be notified and decide to participate in real-time messaging. IM may include video or audio. Video exchange, of course, requires cameras. Underlying this application requires a full-duplex connection between destination and host.

unique index

An index in which the index key can have only one pointer value (row) associated with it.

What are the two types of data that can flow through the circuit

Analog and digital

The probability of detecting an error, given that one has occurred, using parity checking is about: a. 100% b. 0% c. 50% d. 75% e. 98%

Answer: C

All three parts (request line, request header, request body) of an HTTP request from a web browser to a web server are required when a request is made.

Answer: False

One major drawback to a client-server network lies in the fact that client-server networks enable software and hardware from different vendors to be used together.

Answer: False

The World Wide Web was conceived at University of Utah as part of the development of the Internet.

Answer: False

The application architecture called the distributed computing model uses the "thick" client approach.

Answer: False

The earliest data communications networks were client-server networks.

Answer: False

The two-tier e-mail architecture does not require any application software on the client computer.

Answer: False

To use the Web, each client computer requires a data link layer software package called a Web browser.

Answer: False

In a client-server network, the presentation logic is the responsibility of the client computer.

Answer: True

In the three-tier architecture, the software on the client computer is responsible for the presentation logic, an application server is responsible for the application logic and a separate database server is responsible for the data access logic and data storage.

Answer: True

Middleware is the software that sits between the application software on the client and the application software on the server.

Answer: True

The four general functions of any application program are: data storage, data access logic, application logic and presentation logic.

Answer: True

The two functions of middleware are to: 1) provide a standard way of communicating that can translate between software from different vendors, and 2) manage the message transfer between clients and servers so that clients do not need to 'know' which server contains the application's data.

Answer: True

Web-based e-mail like Hotmail is an example of three-tier client-server architecture that provides access to e-mail messages.

Answer: True

determinant

Any attribute in a specific row whose value directly determines other values in that row.

Which of the following TCP/IP model layers combines four OSI model layers? Internet Layer Network Interface Layer Application Layer Transport Layer

Application Layer

What is bandwidth? What is the bandwidth in a traditional North American telephone circuit?

Bandwidth refers to a range of frequencies. It is the difference between the highest and the lowest frequencies in a band; thus the bandwidth of human voice is from 20 Hz to 14,000 Hz or 13,880 Hz. The bandwidth of a voice grade telephone circuit is from 0 to 4000 Hz, or 4000 Hz; however, not all of this is available for use by telephone or data communications equipment. To start, there is a 300-hertz guardband at the bottom of the bandwidth and a 700-hertz guardband at the top. These prevent data transmissions from interfering with other transmissions when these circuits are multiplexed using frequency division multiplexing. This leaves the bandwidth from 300 to 3300 hertz or a total of 3000 Hz for voice or data transmission.

Sending multiple bits simultaneously in analog form

Can assign different amplitudes, frequencies, or phase degrees to different bits Can only go so far before differences become too small to distinguish from noise Can also combine modulation techniques in same transmission

false

Ethernet is a character-oriented data link protocol

Briefly describe how even parity and odd parity work.

Even parity is when the seven bits of an ASCII character have an even (2, 4, or 6) number of 1s, and therefore a 0 is placed in the eighth parity position. Odd parity is when the seven bits of an ASCII character have an odd (1, 3, 5, or 7) number of 1s, and therefore a 1 is placed in the eighth parity position.

A large corporate office is looking to place smaller network closets around campus to handle switching for remote workstations. To which of the following is this referring?

IDF

combining several low speed circuits to enable them to be transmitted across one high speed circuit

Inverse multiplexing means:

What is the term used to describe the placing of two or more signals on a single circuit?

Multiplexing is the term used to describe the placing of two or more signals on a single circuit.

false

Parity checking can only detect an error when an even number of bits are switched.

wavelength division multiplexer

The type of multiplexer that divides the circuit horizontally into different light frequencies that are transmitted simultaneously across many channels is a:

20 to 14,000 Hz

The typical range of human hearing is:

synonym

The use of different names to identify the same object, such as an entity, an attribute, or a relationship; should generally be avoided.

What is the purpose of a data communications standard?

The use of standards makes it much easier to develop software and hardware that link different networks because software and hardware can be developed one layer at a time. The software or hardware defined by the standard at one network layer can be easily updated, as long as the interface between that layer and the ones around it remains unchanged.

physical data format

The way in which a computer "sees" (stores) data.

logical data format

The way in which a human being views data.

5 types of digital transmission

Unipolar - always positive/0 or negative/0 volts Bipolar (NRZ) - positive voltage = 1, negative voltage = 0 - never returns to zero Bipolar (RZ) - voltage returns to zero in between each symbol, which provides an error checking opportunity Bipolar: Alternate Mark Inversion (AMI) - Manchester encoding - used by ethernet - signal is changed from high to low or low to high in the middle of a time splice - less susceptible to errors going unnoticed

3 predominant coding schemes in use today

United States of America Standard Code for Information Interchange (USASCII, or more commonly, ASCII) - most popular for data communications ISO 8859 - includes ASCII codes plus non-English letters - HTML often uses this scheme Unicode - UTF-8 and UTF-16 are two different versions

fiber optic cable

Which of the following media has the lowest error rates and the highest transmission speeds?

infrared

Which of the following media is the least secure?

Serial transmission is slower than parallel transmission.

Which of the following statements is correct?

bipolar

Which type of digital signaling would experience fewer errors because it has more distinct signals?

Describe how data could be transmitted using amplitude modulation.

With amplitude modulation (AM) (also called amplitude shift keying (ASK)), the amplitude or height of the wave is changed. One amplitude is defined to be zero, and another amplitude is defined to be a one.

modulation

____________ refers to changing the shape of the sound wave in different ways to represent a 1 or a 0.

Propagation delay

______________ refers to the time it takes for a signal to travel from sender to recipient (highly exaggerated with satellite transmission).

30. The height of a sound wave is called its: a. frequency b. phase c. amplitude d. bandwidth e. furlong

amplitude

The height of a sound wave is called its : bandwidth phase frequency amplitude furlong

amplitude

11. Another term for the weakening of a signal over distance is: a. turnaround time b. propagation delay c. dispersion d. insulation e. attenuation

attenuation

Another term for the weakening of a signal over distance is: attenuation propagation delay insulation turnaround time dispersion

attenuation

The loss of power a signal suffers as it travels from the transmitting computer to a receiving computer is: a. white noise b. spiking c. attenuation d. intermodulation noise e. echo

attenuation

Another term for impulse noise is: a. Gaussian noise b. spikes c. attenuation d. cross-talk e. intermodulation noise

b. spikes

In a _________ , more than one data bit is changed by the error-causing condition. a. burst error b. data rate shift c. Trellis-coded modulation d. uniform distribution e. amplitude key shift

burst error

The probability of detecting an error, given that one has occurred, using parity checking is about: a. 100% b. 0% c. 50% d. 75% e. 98%

c. 50%

Which of the following is not a property of a WAN: connects backbone networks and MANS. spans hundreds or thousands of miles provides data transmission speeds from 56Kbps to 10Gbps. connects a group of computers in a small geographic area such as room, floor, building or campus. uses leased lines from IXCs like ATT, MCI, and Sprint.

connects a group of computers in a small geographic area such as room, floor, building or campus.

With __________ ARQ, the sender immediately sends the next message or packet of data. a. continuous b. immediate c. open window d. stop-and-wait e. halt and be recognized (HBR)

continuous

what does a codec do?

converts an analog voice signal into digital form, converts it back at the receiving end. used by phone system.

19. Which of the following Structured English statements is an advanced form of an IF statement? a. action statement b. For statement c. While statement d. Case statement e. Do statement

d. Case statement

____________ refers to bits that have been changed, in error, from 1 to 0, or vice versa, in a data transmission. a. Contracted bits b. Polled bits c. Inverse multiplexed bits d. Flipped bits e. Bit delineation

d. Flipped bits

22. Most NoSQL data stores were created to address problems associated with storing large amounts of distributed data in __________. a. SQL Server b. ORDBMSs c. OODBMSs d. RDBMSs e. MySQL

d. RDBMSs

3. _____ has emerged as the standard for the design of object-oriented systems. a. Java b. C++ c. VisualBasic d. UML e. Microsoft .NET

d. UML

14. When a global data area exists outside individual objects, the resulting system has _____ interaction coupling. a. stamp b. data c. content or pathological d. common or global e. control

d. common or global

23. _________ is primarily designed for supporting the decision making systems. a. Rational DBMS b. Object Relational DBMS c. Object-Oriented DBMS d. Microsoft SQL Server e. NoSQL

e. NoSQL

A(n) _________ is a LAN that uses the same technologies as the Internet but is provided to invited users outside the organization who access it over the Internet. MAN BN extranet intranet WAN

extranet

Microwave transmission

extremely high-frequency radio communication beam that is transmitted over a direct line-of-sight path between any two points stations can be place approx. 25 - 50 miles apart

Which of the following would be considered a type of wireless media coaxial cable unshielded twisted pair microwave shielded twisted pair fiber optics

microwave

Which of the following would be considered a type of wireless media? coaxial cable unshielded twisted pair microwave fiber optics shielded twisted pair

microwave

Which of the following would be considered a type of wireless media? microwave fiber optics coaxial cable unshielded twisted pair shielded twisted pair

microwave

Which of the following is not an error detection method used in the data link layer? a. parity checking b. cyclic redundancy checking c. CRC-32 d. pulse code checking e. odd parity

pulse code checking

end-user data is __ a. raw facts about the end-user b. raw facts of interest to the end-user c. data about data d. accurate, relevant and timely information

raw facts of interest to the end-user

a __ is a logically connected set of one or more fields that describes a person, place, or thing (a) database (c) record (b)column (d)file

record

On digital circuits, we use _________ to reshape the incoming signal and prevent attenuation. a. amplifiers b. repeaters c. multiplexers d. digitizers e. modems

repeaters

35. ____________ is a modulation technique that combines two different amplitude combinations with eight different phase combinations modulation to send four bits per wave, or symbol. a. quadrature amplitude modulation b. time division multiplexing c. synchronous digital line control d. pulse code modulation e. baseband signaling

quadrature amplitude modulation

49. _____________ refers to the difference between the original analog data and the approximation of that data using the techniques for translating from analog data to digital signals. a. quantizing error b. handshaking phase c. modulating frequency d. POTS anomaly e. amplitude Trellis effect

quantizing error

the response of the DBMS to a query is the __ a. ad hoc query c. query result set b. ad hoc response d. integrated view of the data

query result set

XML data is __ a. structured c. unstructured b. multistructured d. semistructured

semistructured

most data you encounter is best classified as __ a. structured c. unstructured b. semistructured d. historical

semistructured

23. When all bits of a character are transferred one after another, the bits are transferred in ___________ mode. a. serial b. frequency division c. multiplexing d. parallel e. full complex

serial

24. Which of the following statements is correct? a. Parallel transmission is most often used for sending data on a circuit that is made up of one wire. b. Parallel transmission is distinguished from serial transmission by the fact that the transmitting device sends a single bit, then a second bit, and so on, until all the bits are transmitted. c. Parallel transmission is only used for analog data. d. Serial transmission is considerably slower than parallel transmission. e. Parallel transmission is the same as serial transmission.

serial transmission is considerably slower than parallel transmission

In the Internet model, the application layer corresponds to the ________ layer(s) of the OSI model. application and presentation application layer network, transport and presentation session, presentation and application data link and network

session, presentation and application

7. A(n) __________ circuit is another name for a multipoint configuration. a. analog b. dedicated c. point-to-point d. shared e. simplexed

shared

Satellite transmission

similar to microwave, except instead of transmission involving another nearby microwave dish antenna, it involves a satellite many miles in space (low-earth orbit [LEO]) *raindrop attenuation* is an issue in heavy rains

a desktop database is a __ database a. single-user c. workgroup b. multiuser d. distributed

single-user

The fourth layer of the OSI model is called the __________ layer. presentation session transport network data link

transport

Which layer of the OSI model is responsible for ensuring that all packets sent are received by the destination station by dealing with end-to-end issues? physical application presentation session transport

transport

Symbol rate

Number of symbols sent over the circuit per second

Digital Subscriber Line (DSL)

One approach to changing the way data are transmitted in the local loop to provide higher-speed data transfer combines analog transmission and FDM to provide a set of voice and data circuits

true

Overhead bits are used for error checking and marking the start and end of characters and packets.

Which of the following technologies is used to connect public networks using POTS lines? PSTN OC12 cable OC3

PSTN

How is data transmitted in parallel?

Parallel mode is the way the internal transfer of binary data takes place inside a computer. If the internal structure of the computer is 8-bit, then all eight bits of the data element are transferred between main memory and the central processing unit simultaneously on 8 separate connections. The same is true of computers that use a 32-bit structure; all 32 bits are transferred simultaneously on 32 connections.

Describe how data could be transmitted using phase modulation.

Phase modulation (PM) (also called phase shift keying (PSK)), is the most difficult to understand. Phase refers to the direction in which the wave begins. Until now, the waves we have shown start by moving up and to the right (this is called a 0º phase wave). Waves can also start down and to the right. This is called a phase of 180º. With phase modulation, one phase is defined to be a zero and the other phase is defined to be a one.

POTS

Plain Old Telephone Service Refers to the telephone system

false

Polling is the process of permitting all clients to transmit or receive at any time.

At which of the following layers of the OSI model does ASCII work? Transport Application Presentation Session

Presentation

false

Private dedicated lines are more prone to error than dialup lines.

15. ______________ refers to the time it takes for a signal to travel from sender to recipient (highly exaggerated with satellite transmission). a. Line-of-sight effect b. Multimode index c. Saturation effect d. Raindrop attenuation e. Propagation delay

Propagation delay

Which of the following network media connectors can use a MAXIMUM of two copper wire pairs? MTRJ RJ-45 F-connector RJ-11

RJ-11

data

Raw facts, that is, facts that have not yet been processed to reveal their meaning to the end user.

explain the differences between parallel and serial transmission

Serial sends bit by bit over a single wire while parallel uses several wires and sends bits simultaneously. Serial mode is slower than parallel mode - most of the time

What is Telnet, and why is it useful?

Telnet enables users on one computer to login into other computers on the Internet. Once Telnet makes the connection from the client to the server, a user can login into the server or host computer in the same way as that person would if they dialed in with a modem; the user must know the account name and password of an authorized user. Telnet enables a person to connect to a remote computer without incurring long distance telephone charges. Telnet can be useful because it enables access to servers or host computers without sitting at the dedicated computer's keyboard. Most network managers use Telnet to work on their organization's servers, rather than physically sitting in front of them and using the keyboards.

knowledge

The body of information and facts about a specific subject. implies familiarity, awareness, and understanding of information as it applies to an environment. new can be derived from old

Shielding wires

__________ ensure that hardware and software produced by different vendors work together. Intranets Delimiters Standards ASPs RBOCs

Standards

T/F: Satellite communications is a special form of microwave communications

T/F: wireless media has the highest error rate

Which of the following is not an application layer standard? HTML HTTP IMAP T1 POP

CAT6 has how many twisted copper pairs?

Cross-talk: a. occurs when one circuit picks up signals in another b. is always bothersome because it has a high signal strength c. decreases with increased proximity of two wires d. decreases during wet or damp weather e. increases with lower frequency signals

Answer: A

Each server on a network that needs to act as a web server needs an application layer software package called a (n) ______________. a. browser b. application web c. web server d. operating system e. none of the above

Answer: C

What is coding?

Coding is the representation of one set of symbols by another set of symbols. In data communications, this coding is a specific arrangement of binary 0s and 1s used to represent letters, numbers, and other symbols that have meaning.

time-variant data

Data whose values are a function of time. For example, time-variant data can be seen at work when the history of all administrative appointments (date of appointment and date of termination) are tracked.

internal schema

Depicts a specific representation of an internal model, using the database constructs supported by the chosen database. (The internal model is the representation of a database as "seen" by the DBMS. In other words, the internal model requires a designer to match the conceptual model's characteristics and constraints to those of the selected implementation model.)

conncectivity

Describes the classification of the relationship between entities. Classifications include 1:1, 1:M, and M:N.

As part of the five-layer network model used in this textbook, the data link layer sits directly between: a. the physical and the application layers b. the network and the application layers c. the network and transport layers d. the physical and the application layers e. the physical and the network layers

partial dependency

In normalization, a condition in which an attribute is dependent on only a portion (subset) of the primary key.

what does modem stand for?

MODulate/DEModulate

3 levels of Ethernet transmission schemes

Manchester Fast Ethernet Gigabit Ethernet *see lecture notes for more detail*

design trap

Occurs when a relationship is improperly or incompletely identified and, therefore, is represented in a way that is not consistent with the real world. The most common design trap is known as a fan trap.

Serial transmission

Stream of data is sent over a circuit sequentially in a bit-by-bit fashion - only one physical wire slower than parallel transmission

external model

The application programmer's view of the data environment. Given its business-unit focus, an external model works with a data subset of the global database schema.

Which of the following is not a type of synchronous protocol? a. SDLC b. VT100 c. HDLC d. Ethernet e. PPP

VT100

baud

unit of signaling speed

amplitude

The height of a sound wave is called its:

With odd parity (assume that the parity bit (in bold) has been placed at the end of each of the following) and a 7-bit ASCII code, which of the following is incorrect? a. 01101011 b. 00011011 c. 00100101 d. 10110110 e. 11111110

00011011

Which of the following is the MAXIMUM potential speed of CAT5e UTP cable? 100BaseT 1000BaseT 100BaseFX 10BaseT

1000BaseT

39. The typical range of human hearing is: a. 0 to 4,000 Hz b. 0 to 1,200 Hz c. 20 to 14,000 Hz d. 0 to 300 Hz e. 0 to 56,000 Hz

20 - 14,000 Hz

third normal form 3NF

2NF and no nonkey attribute is functionally dependent on another nonkey attribute; that is, it cannot include transitive dependencies.

what is the formula for calculated the number of symbols needed per bit

2^n n=number of bits

Bandwidth of a standard telephone line

4000 Hz

ad hoc query

A "spur-of-the-moment" question.

table

A (conceptual) matrix composed of intersecting rows (entities) and columns (attributes) that represents an entity set in the relational model.

object/relational database management system O/RDBMS

A DBMS based on the extended relational model (ERDM). The ERDM, championed by many relational database researchers, constitutes the relational model's response to the OODM. This model includes many of the object-oriented model's best features within an inherently simpler relational database structural environment.

Customer premises equipment (CPE)

A DSL modem It is first an FDM device that splits the physical circuit into three logical circuits: a standard voice circuit for phone calls, an upstream data circuit, and a downstream circuit

field

A character or group of characters (alphabetic or numeric) that defines a characteristic of a person, place, or thing. For example, a person's Social Security number, address, phone number, and bank balance all constitute fields.

attribute

A characteristic of an entity or object. An attribute has a name and a data type.

What is the maximum data rate of an analog circuit with a 10 MHz bandwidth using 64-QAM and V.44?

A circuit with a 10 MHz bandwidth using 64-QAM can provide up to 60 Mbps. A V.44 modem can provide as much as 6:1 compression ratio, depending on the type of data sent. Thus, the maximum data rate of 64-QAM with compression is 360 Mbps.

record

A collection of related (logically connected) fields.

structural dependence

A data characteristic that exists when a change in the database schema affects data access, thus requiring changes in all access programs.

structural independence

A data characteristic that exists when changes in the database schema do not affect data access.

data dependence

A data condition in which the data representation and manipulation are dependent on the physical data storage characteristics.

transactional database

A database designed to keep track of the day-to-day transactions of an organization.

distributed database

A logically related database that is stored over two or more physically independent sites

physical model

A model in which the physical characteristics (location, path, and format) are described for the data. Both hardware- and software-dependent.

composite key

A multiple-attribute key.

What is the purpose of multiplexing?

A multiplexer puts two or more simultaneous transmissions on a single communication circuit. Multiplexing a voice telephone call means that two or more separate conversations are sent simultaneously over one communication circuit between two different cities. Multiplexing a data communication network means that two or more messages are sent simultaneously over one communication circuit. In general, no person or device is aware of the multiplexer; it is "transparent."

workgroup database

A multiuser database that supports a relatively small number of users (usually fewer than 50) or that is used for a specific department in an organization.

file

A named collection of related records.

What is a network computer?

A network computer supports Internet access but has no hard disk local storage.

query language

A nonprocedural language that is used by a DBMS to manipulate its data. An example of a query language is SQL.

iterative process

A process based on repetition of steps and procedures.

denormalization

A process by which a table is changed from a higher level normal form to a lower level normal form. Usually done to increase processing speed. Potentially yields data anomalies.

normalization

A process that assigns attributes to entities in such a way that data redundancies are reduced or eliminated.

data management

A process that focuses on data collection, storage, and retrieval. Common data management functions include addition, deletion, modification, and listing.

recursive relationship

A relationship that is found within a single entity type. For example, an EMPLOYEE is married to an EMPLOYEE or a PART is a component of another PART.

non-identifying relationship

A relationship that occurs when the primary key of the dependent (many side) entity does not contain the primary key of the related parent entity. Also known as a weak relationship.

dependency diagram

A representation of all data dependencies (primary key, partial, or transitive) within a table.

conceptual schema

A representation of the conceptual model, usually expressed graphically

database

A shared, integrated computer structure that houses a collection of related data. contains end-user data (raw facts) and metadata.

Boyce-Codd normal form BCNF

A special form of third normal form (3NF) in which every determinant is a candidate key. A table that is in BCNF must be in 3NF.

logical design

A stage in the design phase that matches the conceptual design to the requirements of the selected DBMS and is, therefore, software-dependent. It is used to translate the conceptual design into the internal model for a selected database management system, such as DB2, SQL Server, Oracle, IMS, Informix, Access, and Ingress.

surrogate key

A system-assigned primary key, generally numeric and auto-incremented.

entity instance

A term used in ER modeling to refer to a specific table row.

entity relationship diagram ERD

A term used in ER modeling to refer to a specific table row.

islands of information

A term used in the old-style file system environment to refer to independent, often duplicated, and inconsistent data pools created and managed by different organizational departments.

mandatory participation

A term used to describe a relationship in which one entity occurrence must have a corresponding occurrence in another entity. Example: EMPLOYEE works in DIVISION. (A person cannot be an employee if he or she is not assigned to a company's division.)

Baud rate

A unit of signaling speed used to indicate the number of times per second the signal on the communication circuit changes AKA symbol rate

relationship

An association between entities.

composite attribute

An attribute that can be further subdivided to yield additional attributes. For example, a phone number (615-898-2368) may be divided into an area code (615), an exchange number (898), and a four-digit code (2368).

false

Another term for stop-and-wait ARQ is sliding window.

attenuation

Another term for the weakening of a signal over distance is:

Harmonic distortion can be prevented by a. tuning equipment b. moving wires c. increasing guardbands d. increasing signal strength e. using a high-speed circuit

Answer: A

A(n) _________-tiered architecture uses only two sets of computers: one set of clients and one set of servers. a. one b. two c. three d. five e. n

Answer: B

An application program function is __________, or the processing required to access data. a. data storage b. data access logic c. application logic d. presentation logic e. application access storage

Answer: B

Errors on a network can occur: a. only on dial-up type of circuits b. because of noise on the line c. only on poorly maintained networks d. only due to Gaussian noise e. only due to lightning strikes

Answer: B

A request header for an HTTP request starts with a command, such as GET, and ends with the HTTP version number that the browser understands.

Answer: False

Which of the following TCP/IP model layers does the OSI model Presentation layer map to? Internet Network Interface Application Transport

Application

true

Attenuation refers to the loss of signal strength.

Which of the following is not a controlled access method of media access control? a. Token passing b. CSMA/CD c. polling d. roll call polling e. hub polling

Which of the following is true with respect to the data link layer? a. It accepts streams of bits from the application layer. b. It is responsible for getting a message from one computer to another (one node to another) without errors. c. It does not perform error detection. d. It performs routing functions. e. It organizes data from the physical layer and passes these coherent messages to the application layer.

data warehouse

Bill Inmon, the acknowledged "father of the data warehouse," defines the term as "an integrated, subject-oriented, time-variant, nonvolatile collection of data that provides support for decision making

BYOD stands for Build Your Own Device Build Your Own Database Bring Your Own Device Bring Your Own Database

Bring Your Own Device

Briefly describe how checksum works.

Checksum error checking adds a checksum (typically 1 byte) is added to the end of the message. The checksum is calculated by adding the decimal value of each character in the message, dividing the sum by 255, and then using the remainder as the checksum. The same approach is used at the receiving end. If the receiver gets the same result, the block has been received correctly.

Codec

Code/Decode used to send analog voice data over a digital circuit in the same way that a pair of modems is used to translate data to send across the circuit

true

Contention is commonly used with Ethernet local area networks.

true

Controlled access MAC approaches work better in a large network with high usage.

metadata

Data about data, that is, data concerning data characteristics and relationships

Take-aways for management

Digital is better (see reasons at beginning of chapter) Because analog and digital data is able to converge in physical networks, voice telecommunications is increasingly under the purview of IS organizations Consolidation of manufacturers of networking equipment for organizations and for telephone companies

true

Eliminating jitter to generate a pure carrier signal in an analog circuit is impossible

codec

Equipment used to transform analog voice signals to digital signals and digital signals to analog signals.

because of noise on the line

Errors on a network can occur: -only on dial-up type of circuits -because of noise on the line -only on poorly maintained networks -only due to Gaussian noise -only due to lightning strikes

A local area network (LAN) connects other LANs and backbone networks (BNs) located in different areas to each other and to wide area networks in a span from 3 to 30 miles. True False

False

ASCII is the least popular code for data communications. TRUE/FALSE

False

An intranet is a LAN that uses Internet technologies and is publicly available to people outside of the organization. True False

False

Ethernet is an example of a network layer protocol. True False

False

Frequency division multiplexing divides the circuit into a set of different time slots. TRUE/FALSE

False

true

For effective error detection and correction, extra error detection "data" must be included with each message

Frequency division multiplexing (FDM)?

Frequency division multiplexing can be described as dividing the circuit "horizontally" so that many signals can travel a single communication circuit simultaneously. The circuit is divided into a series of separate channels, each transmitting on a different frequency, much like series of different radio or TV stations. All signals exist in the media at the same time, but because they are on different frequencies, they do not interfere with each other.

operates by dividing the signal into different frequencies

Frequency division multiplexing:

false

Gaussian noise is a special type of attenuation.

9100 Hz

If the highest frequency of a circuit is 10KHZ and the lowest frequency is 900 Hz, the bandwidth available for this circuit is:

What is 64- QAM?

If we use 64-QAM, the bit rate is six times the symbol rate. A circuit with a 10 MHz bandwidth using 64-QAM can provide up to 60 Mbps.

attribute domain

In data modeling, refers to the construct used to organize and describe an attribute's set of possible values.

domain

In data modeling, refers to the construct used to organize and describe an attribute's set of possible values.

false

In data transmission, data errors are uniformly distributed in time.

Suppose your organization was contemplating switching from a host-based > client-server. What problems would you foresee?

Infrastructure supporting cabling hardware and software will need to be redesigned to support the client-server approach to the architecture. Someone would need to be designated to manage what would now become the local area network, so there may be a personnel impact. Security would be one area of concern, since processing can be done on individual workstations. There may be somewhat greater complexity of upgrades, although newer software is reducing the impact of this kind of problem.

What is the function of inverse multiplexing (IMUX)?

Inverse multiplexing (IMUX) combines several low speed circuits to make them appear as one high-speed circuit to the user.

Which of the following is not true about ITU-T: Its membership is limited to U.S. telephone companies It is based in Geneva, Switzerland It is the technical standards-setting organization of the United Nations International Telecommunications Union It is the International Telecommunications Union â€" Telecommunications Group Its membership is comprised of representatives from over 200 member countries

Its membership is limited to U.S. telephone companies

A router operates at which of the following layers of the OSI model? Layer 2 Layer 4 Layer 5 Layer 3

Layer 3

hardware independence

Means that a model does not depend on the hardware used in the implementation of the model. Therefore, changes in the hardware will have no effect on the database design at the conceptual level.

What is media access control, and why is it important?

Media access control handles when the message gets sent. Media access control becomes important when several computers share the same communication circuit, such as a point-to-point configuration with a half duplex line that requires computers to take turns, or a multipoint configuration in which several computers share the same circuit. Here, it is critical to ensure that no two computers attempt to transmit data at the same time -- or if they do, there must be a way to recover from the problem. Media access control is critical in local area networks.

true

Media access controls refer to the need to control when computers transmit.

Guided media

Media in which the message flows through a physical media such as a twisted pair wire, coaxial cable, or fiber-optic cable The media "guides" the signal

Wireless media

Media in which the message is broadcast through the air, such as microwave or satellite

Modem

Modulator/Demodulator converts a digital signal into an analog signal that can be transmitted over phone lines

query result

The collection of data rows that are returned by a query.

Symbol rate

The frequency at which symbols, representing bits, are sent through a circuit - 64 Hz sends 64,000 symbols per second

data definition language DDL

The language that allows a database administrator to define the database structure, schema, and subschema.

True

True/False: A walkie-talkie is an example of half-duplex transmission.

What data compression standard uses Lempel-Ziv encoding? Describe how it works.

V.42bis, the ISO standard for data compression, uses Lempel-Ziv encoding. As a message is being transmitted, Lempel-Ziv encoding builds a dictionary of two, three, and four character combinations that occur in the message. Any time the same character pattern reoccurs in the message, the index to the dictionary entry is transmitted rather than sending the actual data. V.42bis compression can be added to almost any modem standard; thus a V.32 modem providing a data rate of 14,400 bps, could provide a data rate of 57,600 bps when upgraded to use V.42bis.

46. ______ is a modem standard that uses Lempel-Ziv encoding to compress data. a. V.22 b. V.44 c. V.32bis d. V.34 e. RS 232

V.44

true

When the signals from two circuits combine to form a new signal that falls into a frequency band reserved for another signal, this is called, intermodulation noise.

strong relationship

When two entities are existence-dependent; from a database design perspective, this exists whenever the primary key of the related entity contains the primary key of the parent entity.

true

When we amplify the signal on an analog circuit, we also amplify any noise that is present on the circuit.

functional dependence

Within a relation R, an attribute B is functionally dependent on an attribute A if and only if a given value of the attribute A determines exactly one value of the attribute B. The relationship "B is dependent on A" is equivalent to "A determines B" and is written as A B.

Is there any difference in the error rates of lower-speed lines and of higher-speed lines?

Yes, normally lower speed lines have higher error rates because (1) leased lines can be conditioned to prevent noise, but dial-up lines can not and (2) dial-up lines have less stable transmission parameters.

Data rate signaling

___________ is not a type of digital signaling technique.

___________ is the basic physical layout of the circuit. configuration circuit plan circuit configuration circuit design point-to-point configuration

circuit configuration

Codec refers to: a. codependent decreasing compression b. co- Digital Equipment Corporation c. Codd's laws for data relations d. code/decode e. continuous operational digital energy communication

code/decode

Voice over Internet Protocol (VoIP)

commonly used to transmit phone conversations over digital networks uses digital telephones w/ built-in codecs - so can be directly connected into a LAN Must be able to operate in emergencies to call 911 ---must have uninterrupted power supplies (UPS)

Calculating the actual throughput of a data communication network is: a. not normally required for synchronous networks because they are so fast b. complex because many factors affect throughput c. simple because packet size is the primary factor affecting throughput d. not needed for satellite-based networks e. far less complicated if the system operates on a contention basis

complex because many factors affect throughput

computers wait until the circuit is free before they send data

simplex transmission

data flows in one direction only (ex. radio or cable TV broadcasts)

As the number of symbols increases, it becomes harder to ____________

detect

2. Two fundamentally different types of data are: a. DSL and ADSL b. asymmetric and symmetric c. Microsoft and IBM d. digital and analog e. local area and wide area

digital and analog

When a signal is reflected back to the transmitting equipment, it is called a(n) _________. a. white noise b. echo c. crosstalk d. attenuation e. impulse noise

echo

by twisting two wires together, it reduces ______________

electromagnetic interference

T/F: fiber optic cables are very fragile

false

Fiber optic cable

high-speed streams of light pulse from lasers or LEDs and carry information inside hair-thin strands of glass

internal model

in database modeling, refers to a level of data abstraction that adapts the conceptual model to a specific DBMS model for implementation.

41. To get more "bandwidth" in a digital transmission, you must: a. increase the range of frequencies available for a transmission b. increase the loudness per transmission c. decrease the bits per second transmission speed d. increase the phase shifts per transmission e. increase the baud rate per transmission

increase the range of frequencies available for a transmission

relationship degree

indicates the number of entities or participants associated with a relationship. A relationship degree can be unary, binary, ternary, or higher level.

__ is the body of information and facts about a specific subject a. Data b. Information c. Knowledge d. A database

knowledge

Bit rate

number of bits transmitted per second

26. With which type of digital signaling does the signal always return to zero volts after each bit? a. Non-return-to-zero signaling b. Unipolar signaling c. Return-to-zero signaling d. Data rate signaling e. Huffman encoding signal

return-to-zero signaling

With which type of digital signaling does the signal always return to zero volts after each bit?

return-to-zero signaling

T/F: A walkie-talkie is an example of half-duplex transmission.

true

An application architecture is the way in which the functions of the application layer are performed solely by the clients in the network.

Answer: False

As the demand for more and more network applications grow; host-based computing becomes the best solution.

Answer: False

Host-based and client-based networks are similar in that the client computer performs most of the work.

Answer: False

The Simple Mail Transfer Protocol is the least commonly used e-mail standard.

Answer: False

Using the POP standard for client to server e-mail communication, the e-mail messages remain on the server computer.

Answer: False

A network computer is designed primarily to communicate using Internet based standards, but has no hard disk. It has only limited functionality.

Answer: True

What is the capacity of a digital circuit with a symbol rate of 10 MHz using Manchester encoding?

B = s * n B = (10 MHz) * 1 bit per symbol Capacity is 10 Mbps

________________ separate channels to reduce interference between channels in frequency division multiplexing.

Guardbands

Which of the following TCP/IP model layers does the OSI model Data Link layer map to? Application Internet Network Interface Transport

Network Interface

False

True/False: Only the sender of a data transmission needs to be concerned about the rules or protocols that govern how it communicates with the receiver.

True

True/False: The data link layer accepts messages from the network layer and controls the hardware that transmits them.

True

True/False: The predominant method of transferring information internally in a computer is via parallel mode.

True

True/False: The simplest method for error correction is retransmission.

True

True/False: WDM is a version of FDM used in fiber-optic cables.

True

True/False: When we amplify the signal on an analog circuit, we also amplify any noise that is present on the circuit.

False

True/False: With contention, a computer does not have to wait before it can transmit. A computer can transmit at anytime. True

What is cloud computing?

With cloud computing, a company contracts with another firm to provide software services over the Internet, rather than installing the software on its own servers. The company no longer buys and manages its own servers and software, but instead pays a monthly subscription fee or a fee based on how much they use the application.

Guardbands

________________ separate channels to reduce interference between channels in frequency division multiplexing.

Time division multiplexing (TDM)

a communication circuit is shared among two or more computers by having them take turns, dividing the circuit "vertically" A character is taken from each computer in turn doesn't require guardbands

20. The audience for pseudocode is the _____. a. analyst b. programmer c. manager d. user e. customer

b. programmer

On digital circuits, we use _________ to reshape the incoming signal and prevent attenuation. a. amplifiers b. repeaters c. multiplexers d. digitizers e. modems

b. repeaters

Another term for impulse noise is: Select one: a. Gaussian noise b. spikes c. attenuation d. cross-talk e. intermodulation noise

b. spikes

21. Which one in the following list is an example of NOSQL data store . a. Oracle b. SQL Server c. Access d. OODBMS e. Google's Big Table

e. Google's Big Table

The network layer of the Internet model uses the _____________ protocol to route messages though the network. Select one: a. HTTP b. FTP c. SMTP d. TCP e. IP

e. IP

Data is physically transmitted from one computer or terminal to another in the ________ layer. data link terminal application transport physical

physical

historically, a manual file system was composed of a system of file folders and filing cabinets

true

initially the files within a computer file system were similar to manual files

true

metadata present a more complete picture of the data in the database than the data itself

true

one disadvantage of a database system over previous data management approaches is increased costs

true

the only way to access the data in the database is through the DBMS

true

the same data might be simultaneously structured and unstructured depending on the intended processing

true

we are now said to be entering the "knowledge age"

true

Compare and contrast two-tiered, three-tiered, and n-tiered client server architectures. What are the technical differences, and what advantages and disadvantages do each offer?

two-tiered architectures have only clients and servers. three-tiered architectures typical separate (1) presentation logic, (2) application logic, and (3) and data access logic and storage. n-tiered architecture more than one tier may be used to support application logic, typically due to a Web server tier being included. three-tiered or n-tiered architectures place a greater load on the network, but balances server load better and is more scalable.

superkey

Any key that uniquely identifies each row

Physical circuit

The actual wire used to connect devices

guided and wireless (radiated)

The two basic types of media are:

Briefly describe three important coding schemes.

- United States of America Standard Code for Information Interchange (USASCII), or more commonly ASCII, is the most popular code for data communications and is the standard code on most terminals and microcomputers. - There are two types of ASCII; one is a 7-bit code that has 128 valid character combinations, and the other is an 8-bit code that has 256 combinations. - Extended Binary Coded Decimal Interchange Code (EBCDIC) is IBM's standard information code. This code has 8 bits, giving 256 valid character combinations.

How can data communication networks affect businesses?

- being the foundations for distributed systems in which information system applications are divided among a network of computers - facilitate more efficient use of computers and improve the day-to-day control of a business by providing faster information flow, aiding strategic competitive advantage - provide message transfer services to allow computer users to talk to one another via email

Describe the four basic functions of an application software package.

- data storage - data access logic - application logic - presentation logic

Three important applications of data communication networks in business and personal use

- email - videoconferencing - the Internet

What are the different types of application architectures?

- host-based (all processing done on host system and all data on host with terminals providing access) - client-based (with processing done on client and all data stored on server), - client-server (balanced processing; usually host provides data access and storage while the client provides application and presentation logic).

In clean, error free, and interference free analog transmission, what three basic factors could be changed to obtain a higher data rate?

--Boost frequency range on the transmission line --Go from two waves per symbol to one wave per symbol --Increase our modulation to send more bits per symbol

Gigabit Ethernet

--SymRate = 125 MHz --Bits/Symbol = 2 (x 4 lines parallel) ---Detection = Voltage levels ---Data Rate = "1Gbps" (Actually 800 Mbps because every 5th bit is a control bit with no actual data)

Which of the following is true about the data link protocol, SDLC: Select one: a. It is a client-server protocol developed by Compaq in 1996. b. It transmits each character independently of one another and includes start and stop bits for each character sent. c. It uses a special bit pattern called a flag at the beginning and end of every frame (or packet). d. It uses a contention media access control protocol and is used in most LANs today. e. It does not have any error detection capabilities.

...c. It uses a special bit pattern called a flag at the beginning and end of every frame (or packet).

What are the four steps to Pulse Amplitude Modulation (PAM)

1. take samples of the varying signal across time 2. measure amplitude of each sample 3. encode amplitude measurement to binary data that is representation of the sample 4. send the discrete, digital data stream of 0's and 1's that approximates the original analog signal

which of the following is MOST commonly used with fiber-optic network backbone 100BaseFX 100BaseT 100BaseCX 100BaseTX

100BasefX

21. Under one type of ASCII, each character is represented by 7 bits. That means that there are ________ valid combinations that can represent different characters. a. 23 b. 256 c. 128 d. 1092 e. 8

128

34. When sending four bits at a time using frequency modulation, the number of different frequency levels that would be needed would be _______. a. 24 b. 16 c. 2 d. 8 e. 4

43. Using TCM that sends 6 bits per each signal and a voice grade line with a bandwidth of 3000 Hz (assume: no noise on the line), the data capacity would be ___________ bits per second. a. 56K b. 6 c. 24,000 d. 500 e. 18,000

18,000

40. __________ is the approximate bandwidth of traditional telephone circuits. a. 30,000 - 40,000 Hz b. 300 - 400 Hz c. 3 - 4 Hz d. 3000 - 4000 Hz e. 9000 - 10000 Hz

3000 - 4000 Hz

4B5B encoding

4 bits are mapped into 5 bits no more than 4 1s or 0s in a row - 5th bit will be the opposite in order to delineate each 4 bit section - helps detect errors

The probability of detecting an error, given that one has occurred, using parity checking is about: a. 100% b. 0% c. 50% d. 75% e. 98%

50%

When sending three bits at a time using frequency modulation, the number of different frequency levels that would be needed would be _______.

19. Which of the following is a byte, under the normal definition? a. 1 b. a special character that is used for Apple computers only c. 0 d. 325 e. 8 consecutive bits, such as 00011100, that represent one unit or character

8 consecutive bits, such as 00011100 that represent one unit or character

50. When converting analog voice data to digital signals, Pulse Code Modulation samples the incoming voice signal _______ times per second. a. 8,000 b. 8 c. 18,000 d. 64 e. 256

8,000

The probability of detecting an error, provided that one has occurred, using cyclic redundancy checking is about: a. 75% b. 0% c. exactly 100% d. 50% e. > 99%

> 99%

class

A collection of like objects with shared structure (attributes) and behavior (methods). A class encapsulates an object's data representation and a method's implementation. Classes are organized in a class hierarchy.

relational database management system RDBMS

A collection of programs that manages a relational database. The RDBMS software translates a user's logical requests (queries) into commands that physically locate and retrieve the requested data. A good RDBMS also creates and maintains a data dictionary (system catalog) to help provide data security, data integrity, concurrent access, easy access, and system administration to the data in the database through a query language (SQL) and application programs.

referential integrity

A condition by which a dependent table's foreign key must have either a null entry or a matching entry in the related table. Even though an attribute may not have a corresponding attribute, it is impossible to have an invalid entry.

transitive dependency

A condition in which an attribute is dependent on another attribute that is not part of the primary key.

full functional dependence

A condition in which an attribute is functionally dependent on a composite key but not on any subset of that composite key.

data inconsistency

A condition in which different versions of the same data yield different (inconsistent) results.

data redundancy

A condition that exists when a data environment contains redundant (unnecessarily duplicated) data.

data independence

A condition that exists when data access is unaffected by changes in the physical data storage characteristics.

logical independence

A condition that exists when the internal model can be changed without affecting the conceptual model. (The internal model is hardware independent because it is unaffected by the choice of computer on which the software is installed. Therefore, a change in storage devices or even a change in operating systems will not affect the internal model.)

physical independence

A condition that exists when the physical model can be changed without affecting the internal model.

true

A conditioned circuit is more expensive than a regular telephone circuit because it has been certified by the carrier to experience fewer errors.

completeness constraint

A constraint that specifies whether each entity supertype occurrence must also be a member of at least one subtype. The completeness constraint can be partial or total. Partial completeness means that not every supertype occurrence is a member of a subtype; that is, there may be some supertype occurrences that are not members of any subtype. Total completeness means that every supertype occurrence must be a member of at least one subtype.

data anomaly

A data abnormality that exists when inconsistent changes to a database have been made. For example, an employee moves, but the address change is corrected in only one file and not across all files in the database.

entity relationship ER model ERM

A data model developed by P. Chen in 1975. It describes relationships (1:1, 1:M, and M:N) among entities at the conceptual level with the help of ER diagrams.

network model

A data model standard created by the CODASYL Data Base Task Group in the late 1960s. It represented data as a collection of record types and relationships as predefined sets with an owner record type and a member record type in a 1:M relationship.

object-oriented data model OODM

A data model whose basic modeling structure is an object.

specialization hierarchy

A hierarchy that is based on the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype. Specialization is based on grouping unique characteristics and relationships of the subtypes.

prime attribute

A key attribute, that is, an attribute that is part of a key or is the whole key.

secondary key

A key that is used strictly for data retrieval purposes. For example, a customer is not likely to know his or her customer number (primary key), but the combination of last name, first name, middle initial, and telephone number is likely to make a match to the appropriate table row.

schema

A logical grouping of database objects (tables, indexes, views, queries, etc.) that are related to each other. Usually belongs to a single user or application.

How does a multipoint circuit differ from a point-to-point circuit?

A point-to-point configuration is so named because it goes from one point to another (e.g., one computer to another computer). These circuits sometimes are called dedicated circuits because they are dedicated to the use of these two computers. In a multipoint configuration (also called a shared circuit), many computers are connected on the same circuit. This means that each must share the circuit with the others, much like a party line in telephone communications. The disadvantage is that only one computer can use the circuit at a time. Multipoint configurations are cheaper than point-to-point configurations.

SQL

A powerful and flexible relational database language composed of commands that enable users to create database and table structures, perform various types of data manipulation and data administration, and query the database to extract useful information.

foreign key

A primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the two tables

atomicity

A property of transactions that states that all parts of a transaction must be treated as a single logical unit of work in which all operations must be completed (committed) to produce a consistent database.

query

A question or task asked by an end user of a database in the form of SQL code. A specific request for data manipulation issued by the end user or the application to the DBMS.

natural key

A real-world, generally accepted identifier used to identify real-world objects. familiar to end users and forms part of their day-to-day business vocabulary.

weak relationship

A relationship that exists when the PK of the related entity does not contain a PK component of the parent entity. Also known as a non-identifying relationship.

identifying relationship

A relationship that exists when the related entities are existence-dependent. Also called a strong relationship or strong identifying relationship because the dependent entity's primary key contains the primary key of the parent entity.

Crow's Foot notation

A representation of the entity relationship diagram using a three-pronged symbol to represent the "many" sides of the relationship.

data model

A representation, usually graphic, of a complex "real-world" data structure. Data models are used in the database design phase of the database life cycle.

constraint

A restriction placed on data. Constraints are normally expressed in the form of rules. Example: "A student's GPA must be between 0.00 and 4.00." Constraints are important because they help to ensure data integrity.

Describe the anatomy of a router. How does a router differ from a computer?

A router consists of a CPU, memory, and ports or interfaces. A router differs from a computer because they are diskless and they don't come with a monitor, keyboard or mouse.

What is a session?

A session can be thought of as a conversation between two computers. When the sender wants to send a message, it first establishes a session with the destination computer. The sender then sends the data packets in order until all data has been sent. Then the session is ended.

What is a virtual server?

A virtual server is one computer that acts as several servers. Using special software like Microsoft Virtual PC, WMWare, or VirtualBox, several operating systems are installed on the same physical computer so that one computer appears as several different ones on the network.

multiplexer

A(n) ___________ divides one high-speed communication circuit into several lower speed circuits for the primary reason of saving communication line costs.

Point to point circuit

AKA *dedicated circuit* Goes from one computer to another used when computers generate enough data to fill the capacity of the circuit

Multipoint circuit

AKA *shared circuit* Many computers on the same circuit - only one can use circuit at a time

Fast Ethernet

AKA -* 100Base-T* --SymRate = 125 MHz --Bits/Symbol = 0.8 (4B5B encoding) ---Detection = Change in voltage level ---Data Rate = 100Mbps --Binary 0 = no voltage change --Binary 1 = step voltage

Manchester

AKA -* 10Base-T* --SymRate = 10 MHz --Bits/Symbol = 1 ---Detection = Direction of voltage change ---Data Rate = 10Mbps

Bandwidth on Demand Interoperability Networking Group

AKA BONDING an IMUX standard that allows clients and hosts to communicate using IMUX most common use of BONDING is room-to-room video conferencing

Amplitude modulation (AM)

AKA amplitude shift keying (ASK) the amplitude is changed - one wave height representing 1 and another representing 0 most suseptible to noise (errors)

Data rate

AKA bit rate calculated by multiplying the number of bits sent on each symbol by the maximum symbol rate

Frequency modulation (FM)

AKA frequency shift keying (FSK) A different wave length is used for a 1 and a 0

Phase modulation (PM)

AKA phase shift keying (PSK)

Local loop

AKA the last mile The wires that run from your home or business to the telephone switch that connects your local loop into the telephone network

Examples of national-level standards bodies (with the legal authority for national standards development and articulation with ISO) are:

ANSI SCC DGN BSI JISC AFNOR BIS CSBTS GOST R SNV DIN

20. ____________ is one of the most commonly used coding schemes used in data transmission. a. ASCII b. ISDN c. MAU d. ATM e. FDM

ASCII

_____________ is an effective way to prevent attenuation. a. Shielding wires b. Adding fluorescent lights c. Adding repeaters or amplifiers to a circuit d. Changing multiplexing techniques e. Shorting a circuit

Adding repeaters or amplifiers to a circuit

Which of the following is true about ISO: It makes technical recommendations about data communications interfaces It is one of the most important standards-making bodies It is based in Geneva, Switzerland Its name stands for International Organization for Standardization All of the other answers

All of the other answers

Statistical time division multiplexing (STDM)

Allows more computers on a circuit than TDM or FDM selection of transmission speed for the multiplexed circuit is based on a statistical analysis of the usage requirements of the circuits to be mutliplexed

Three important characteristics of sound waves that are transmitted through the voice circuit

Amplitude - the height(and depth) of the wave measured in decibles Frequency - length of the wave, measured in waves per second (Hertz or Hz) Phase - refers to the direction in which the wave begins, measured in the number of degrees

With respect to converting digital data into analog signals, AM stands for: Analog Multimode Analytical Mosaic Amplitude Modulation Asynchronous Manchester Anomaly Multiplexing

Amplitude Modulation

___________ is not a function of a data link protocol. a. Media access control b. Message delineation c. Amplitude shift keying d. Indicating when a message starts and stops e. Error control

Amplitude shift keying

ternary relationship

An ER term used to describe an association (relationship) between three entities. Example: A CONTRIBUTOR contributes money to a FUND from which a RECIPIENT receives money.

binary relationship

An ER term used to describe an association (relationship) between two entities. Example: PROFESSOR teaches COURSE.

unary relationship

An ER term used to describe an association within an entity. Example: A COURSE is a prerequisite to another COURSE.

participants

An ER term used to label the entities that participate in a relationship. Example: PROFESSOR teaches CLASS. (The teaches relationship is based on the participants PROFESSOR and CLASS.)

associative entity

An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances.

object

An abstract representation of a real-world entity that has a unique identity, embedded properties, and the ability to interact with other objects and with itself.

How do amplifiers differ from repeaters?

An amplifier takes the incoming signal, increases its strength, and retransmits it on the next section of the circuit. They are typically used on analog circuits such as the telephone company's voice circuits. On analog circuits, it is important to recognize that the noise and distortion are also amplified, along with the signal. Repeaters are commonly used on digital circuits. A repeater receives the incoming signal, translates it into a digital message, and retransmits the message. Because the message is re-created at each repeater, noise and distortion from the previous circuit are not amplified.

multivalued attribute

An attribute that can have many values for a single entity occurrence. For example, an EMP_DEGREE attribute might store the string "BBA, MBA, PHD" to indicate three different degrees held.

single-valued attribute

An attribute that can have only one value.

simple attribute

An attribute that cannot be subdivided into meaningful components.

derived attribute

An attribute that does not physically exist within the entity and is derived via an algorithm. Example: Age = current date - birth date.

nonprime attribute

An attribute that is not part of a key.

candidate key

An attribute, or combination of attributes, that uniquely identifies a row in a relation.

composite entity

An entity designed to transform an M:N relationship into two 1:M relationships. The composite entity's primary key comprises at least the primary keys of the entities that it connects (bridge entity)

key

An entity identifier based on the concept of functional dependence;

existence-independent

An entity that can exist apart from one or more related entities. It must be created first when referencing an existence-dependent table to it.

weak entity

An entity that displays existence dependence and inherits the primary key of its parent entity. Example: A DEPENDENT requires the existence of an EMPLOYEE.

index

An ordered array composed of index key values and row ID values (pointers). used to speed up and facilitate data retrieval. Also known as an index key.

database system

An organization of components that defines and regulates the collection, storage, management, and use of data in a database environment.

desktop database

An organization of components that defines and regulates the collection, storage, management, and use of data in a database environment.

Explain how pulse code modulation (PCM) works.

Analog voice data must be translated into a series of binary digits before they can be transmitted. With PAM-based methods, the amplitude of the sound wave is sampled at regular intervals, and translated into a binary number. The most commonly used type of PAM is Pulse Code Modulation (PCM). With PCM, the input voice signal is sampled 8000 times per second. Each time the input voice signal is sampled, eight bits are generated. Therefore, the transmission speed on the digital circuit must be 64,000 bits per second (8 bits per sample x 8,000 samples per second) in order to transmit a voice signal when it is in digital form.

Answer: A

An N-tiered architecture: a. is generally more "scalable" than a three-tiered architecture b. is generally less "scalable" than a three-tiered architecture c. uses only two sets of computers in which the clients are responsible for the application and presentation logic, and the servers are responsible for the data d. uses exactly three sets of computers in which the client is responsible for presentation, one set of servers is responsible for data access logic and data storage, and application logic is spread across two or more different sets of servers e. puts less load on a network than a two-tiered architecture because there tends to be less communication among the servers

Answer: A

In the three tier architecture the software on the client computer is responsible for____________. a. presentation logic b. application logic c. data access logic d. data storage e. application storage

Answer: A

There are required and optional parts of an HTTP response. They are: a. response status, response header, response body b. response address, response header, response body c. response status, response body d. response address, response header e. response status, response header

Answer: A

To interact with the World Wide Web, a client computer needs an application layer software package called a: a. Web browser b. Web server c. Telnet package d. Uniform Resource Locator package e. Router package

Answer: A

Which of the following media is least susceptible to noise? a. fiber optic cable b. coaxial cable c. twisted pair d. unshielded twisted pair e. shielded twisted pair

Answer: A

With __________ ARQ, the sender immediately sends the next message or packet of data. a. continuous b. immediate c. open window d. stop-and-wait e. halt and be recognized (HBR)

Answer: A

_________ is an application program function that deals with storing and retrieving data. a. data storage b. data access logic c. application logic d. presentation logic e. application access storage

Answer: A

The primary source of error in data communications is: a. echoes b. intermodulation noise c. spikes d. jitter e. cross-talk

Answer: C

Answer: A

Another term for impulse noise is: a. Gaussian noise b. spikes c. attenuation d. cross-talk e. intermodulation noise

Answer: B

In general, controlled approaches: a. work better than contention approaches for small networks that have low usage b. work better than contention approaches for large networks that have high usage c. work better than contention approaches for all sizes of networks d. do not require a host, server, or active monitor to assign media access control e. have many collisions

Answer: B

Marc Andreessen led a team that developed the first graphical Web browser, which was called: a. Internet Explorer b. Mosaic c. Firebird d. Netscape Navigator e. Mozilla

Answer: B

On digital circuits, we use _________ to reshape the incoming signal and prevent attenuation. a. amplifiers b. repeaters c. multiplexers d. digitizers e. modems

Answer: B

One underlying problem with a host-based network is that: a. there are economies of scale because all computer resources are centralized b. the server can get overloaded since it must process all messages c. the architecture is relatively simple and works well d. the server is the one point of control which simplifies security e. clients (terminals) do not require sophisticated hardware/software because they do not perform most of the work in this type of architecture

Answer: B

The idea for a special hypertext network, called the World Wide Web, was conceived of by: a. Microsoft in 1994 as part of the Windows 95 project b. Tim Berners-Lee at the European Laboratory for Particle Physics (CERN) in 1989 c. Vinton Cerf, for the U.S. Department of Defense in 1969 as a network of four computers called ARPANET d. Howard Flieshman of IBM in 1982 as part of the development of the IBM PC e. the University of Minnesota as an extension of Gopher

Answer: B

When a signal is reflected back to the transmitting equipment, it is called a(n) _________. a. jitter b. echo c. crosstalk d. attenuation e. impulse noise

Answer: B

Which of the following is not a controlled access method of media access control? a. Token passing b. CSMA/CD c. polling d. roll call polling e. hub polling

Answer: B

With the "thin client" architecture, when an application changes, only the _________ with the application logic needs to be updated. a. client b. server c. middleware d. hardware e. software

Answer: B

With the two-tier client-server architecture, the client is responsible for the ________ logic and the server is responsible for the ________ logic. a. Application; presentation b. Presentation; data access c. Data access; presentation d. Application; data access e. Presentation; application storage

Answer: B

________ is the process of sending a signal to a client that gives its permission to transmit or asks it to receive. a. Contention b. Polling c. Pooling d. Carrier sense e. CRC

Answer: B

A "thick client" architecture approach: a. always is a two-tier network architecture b. always is an n-tiered architecture c. places all or almost all of the application logic on the client d. places all or almost all of the application logic on the server e. refers to the size of the cable connecting the clients to the network

Answer: C

Client-server architectures: a. cannot connect computers that use different hardware b. are one of the least used network architectures today c. can use middleware to provide a standard way of communicating between software from more than one vendor d. assign the responsibility for the presentation logic to the server e. were the earliest type of network architectures

Answer: C

How are the application architecture functions split up in a client-server network? a. the presentation logic and data storage are on the client, while the data access logic is on the server b. the data storage, data access, and presentation logic are on the client c. the presentation logic is on the client, while the data storage and data access logic are on the server d. the data storage and data access logic are on the client, while the presentation logic are on the server e. the presentation logic and data access logic are on the client, and the data storage is on the server

Answer: C

In a client-server network, _________ gets software from different vendors to work together. a. a front-end processor b. serverware c. middleware d. centerware e. programmer

Answer: C

In a two-tier client-server architecture, a client computer needs to use an application layer software package called a ________________ to send e-mail: a. message transfer agent b. router agent c. user agent d. Webcast package e. gateway agent

Answer: C

The acronym, HTML, refers to: a. Header Markup Language b. Hypertext Markup Locator c. Hypertext Markup Language d. Hypertext Markup Library e. Hypertext Modulating Language

Answer: C

The loss of power a signal suffers as it travels from the transmitting computer to a receiving computer is: a. jitter b. spiking c. attenuation d. intermodulation noise e. echo

Answer: C

With respect to costs for a client-server network, which of the following is true? a. Personal computers used as clients in a client-server network cost about the same as mainframes for the same amount of computing power. b. More network capacity, which costs more money, is required for client-server networks than for client-based networks. c. Experts believe that client server architectures can be complex, but that developing application software for host based architectures is usually cheaper. d. Updating the network with new version of software tends to be less expensive in a client-server network since the software is centralized in one client. e. None of the above

Answer: C

____________ is not a function of a data link protocol. a. Media access control b. Message delineation c. Amplitude shift keying d. Indicating when a message starts and stops e. Error control

Answer: C

______________, or the algorithms or business logic programmed into the application, can be simple or complex depending on the application. a. data storage b. data access logic c. application logic d. presentation logic e. application access storage

Answer: C

__________can obliterate a group of bits, causing a burst error. a. Crosstalk b. Attenuation c. Impulse noise d. Intermodulation noise e. Jitter

Answer: C

A "thin client" architecture approach: a. always is a two-tier network architecture b. always is an n-tiered architecture c. places all or almost all of the application logic on the client d. places all or almost all of the application logic on the server e. refers to the size of the cable connecting the clients to the network

Answer: D

A(n) __________ is the way in which the functions of the application layer software are spread among the clients and servers in the network. a. anonymous FTP b. data access logic c. fat client d. application architecture e. response status architecture

Answer: D

One disadvantage of the ____________ architecture is that places a greater load on the network. a. two-tier b. three tier c. one-tier d. n-tier e. layered

Answer: D

To get a page from the Web, a user must type in a URL, which stands for: a. Unknown Resource Locator b. Unknown Router Location c. Uniform Router Location d. Uniform Resource Locator e. Uniform Resource Library

Answer: D

Which of the following is not an error detection method used in the data link layer? a. parity checking b. cyclic redundancy checking c. CRC-32 d. pulse code checking e. odd parity

Answer: D

Which of the following is true about the data link protocol, Ethernet (IEEE 802.3)? a. it is not very popular b. it is a bit-oriented protocol c. it uses block check characters for error detection d. newer version permits jumbo frames e. it uses parity bits for error detection

Answer: D

With __________ ARQ, the sender pauses for a response from the receiver to alter each message or packet of data. a. open window b. halt and be recognized (HBR) c. sliding window d. stop and wait e. continuous

Answer: D

With a client-based network, one fundamental problem is that: a. the clients each must store all the data b. the server does not have any data storage capability c. the host or server must perform presentation logic, application logic, and data access logic at the same time d. all data on the server must travel to the client for processing e. the clients must perform the data storage logic

Answer: D

________ is the presentation of information to the user and the acceptance of the user's commands. a. data storage b. data access logic c. application logic d. presentation logic e. application access storage

Answer: D

Asynchronous transmission: a. is used to transmit each character simultaneously with all other characters b. has a pre-determined, fixed time between sending characters c. is typically used on multipoint half duplex circuits d. uses a continuous series of start bits as an idle signal e. is also known as start-stop transmission

Answer: E

IMAP (Internet Message Access Protocol): a. is a set of standards that define how email is to be processed between mail servers b. is exactly the same as SMTP c. copies an e-mail message from the client computer's hard disk, deletes it from the client, and stores it on the mail server d. is exactly the same as POP e. permits an e-mail message to remain stored on the mail server even after they have been read by a client computer

Answer: E

Synchronous transmission: a. cannot be used on multipoint circuits b. is used to send one character at a time c. uses start bits before each character to be sent d. uses stop bits after each character to be sent e. is used to transmit a "frame" or "packet" of data at a time

Answer: E

There are optional and required parts of an HTTP request. They are: a. request address, request body b. request address, request header, request body c. request line, request header d. request line, request body e. request line, request header, request body

Answer: E

When the output signal from an amplifier on a circuit is different from the input signal, this is called _________________. a. intermodulation noise b. attenuation c. echo d. jitter e. harmonic distortion

Answer: E

Which of the following is not a general function by any application program? a. data storage b. data access logic c. application logic d. presentation logic e. application access storage

Answer: E

Which of the following is true about roll call polling? a. It can not be modified to increase priority of clients or terminals. b. It does not require a server or host or special device that performs the polling. c. It is also called token passing. d. It is a type of contention approach to media access control. e. It typically involves some waiting because the server has to wait for a response from the polled client or terminal.

Answer: E

A "thin client" approach places most of the application logic on the client.

Answer: False

Investigate the options for having your private cloud as an individual. Hint: Try the Apple Web site.

As of May, 2016, iCloud provides 5GB of free storage that can be used for photos, videos, documents, app data, and more. If you need more space, simply upgrade to a larger storage plan starting with 50GB for just $0.99/month. iCloud can be used on all of your devices, which allows users to sync their data across devices.

the physical and the network layers

As part of the five-layer network model used in this textbook, the data link layer sits directly between: -the physical and the application layers -the network and the application layers -the network and transport layers -the physical and the application layers -the physical and the network layers

cardinality

Assigns a specific value to connectivity. Expresses the range (minimum to maximum) of allowed entity occurrences associated with a single occurrence of the related entity.

Another term for impulse noise is: a. Gaussian noise b. spikes c. attenuation d. cross-talk e. intermodulation noise

Errors on a network can occur: a. only on dial-up type of circuits b. because of noise on the line c. only on poorly maintained networks d. only due to Gaussian noise e. only due to lightning strikes

On digital circuits, we use _________ to reshape the incoming signal and prevent attenuation. a. amplifiers b. repeaters c. multiplexers d. digitizers e. modems

TRIB, an acronym that relates to throughput, stands for: a. Throughput Reduction of Information Barriers b. Transmission Rate of Information Bits c. Throughput Rate of Iso-synchronous Bytes d. Transmission Regulation for Inverse-multiplexing Bands e. Trellis-coded Regulation of Information Bits

When a signal is reflected back to the transmitting equipment, it is called a(n) _________. a. jitter b. echo c. crosstalk d. attenuation e. impulse noise

When a signal is reflected back to the transmitting equipment, it is called a(n) _________. a. white noise b. echo c. crosstalk d. attenuation e. impulse noise

Which of the following is not a type of synchronous protocol? a. SDLC b. VT100 c. HDLC d. Ethernet e. PPP

________ is the process of sending a signal to a client that gives its permission to transmit or asks it to receive. a. Contention b. Polling c. Pooling d. Carrier sense e. CRC

What is the symbol rate of a digital circuit providing 100 Mbps if it uses bipolar NRz signaling?

B = s * n 100 Mbps = s * 1 bit per symbol Symbol rate is 100 Mhz

A backbone network is: Select one: A. a network spanning a geographical area that usually encompasses a city or county area (3 to 30 miles).g B. a high speed central network that connects other networks in a distance spanning up to several miles. C. a group of personal computers or terminals located in the same general area and connected by a common cable (communication circuit) so they can exchange information. D. a network spanning exactly 200 miles with common carrier circuits. E. a network spanning a large geographical area (up to 1000s of miles).

B. a high speed central network that connects other networks in a distance spanning up to several miles.

In ARQ, a NAK: a. is sent by the recipient if the message was received without error b. is sent by the sender at the same time as it sends a data packet c. is sent by the recipient if the message contains an error d. refers to non-asynchronous Kermit technique e. means that the sender should continue with sending the next message

The loss of power a signal suffers as it travels from the transmitting computer to a receiving computer is: a. jitter b. spiking c. attenuation d. intermodulation noise e. echo

The loss of power a signal suffers as it travels from the transmitting computer to a receiving computer is: a. white noise b. spiking c. attenuation d. intermodulation noise e. echo

The primary source of error in data communications is: a. echoes b. intermodulation noise c. spikes d. attenuation e. cross-talk

The probability of detecting an error, given that one has occurred, using parity checking is about: a. 100% b. 0% c. 50% d. 75% e. 98%

Which of the following is true with respect to the data link layer? a. It accepts streams of bits from the application layer. b. It is responsible for encoding the bit-stream as a series of electronic voltages. c. It performs error detection. d. It performs routing functions. e. It organizes data from the physical layer and passes these coherent messages directly to the application layer.

___________ is not a function of a data link protocol. a. Media access control b. Message delineation c. Amplitude shift keying d. Indicating when a message starts and stops e. Error control

____________ is not a function of a data link protocol. a. Media access control b. Message delineation c. Amplitude shift keying d. Indicating when a message starts and stops e. Error control

__________can obliterate a group of bits, causing a burst error. a. Cross-talk b. Attenuation c. Impulse noise d. Intermodulation noise e. White noise

A consultant has been hired to wire a simple small office of ten computers to a layer 2 Ethernet 100BaseT switch. Which of the following cabling will be needed for the installation RG-59 coaxial CAT3 CAT6a Multi-mode fiber

CAT6a

What does codec stand for?

COder/DECoder

Which of the following is not a controlled access method of media access control? a. Token passing b. CSMA/CD c. polling d. roll call polling e. hub polling

CSMA/CD

Which is less expensive: host-based networks or client-server networks? Explain.

Client-server networks are less expensive because in a competitive market involving multiple vendors, software and hardware upgrades cost substantially less. Upgrades for host-based networks are generally very expensive, and occur in what is generally termed a "step function," meaning requiring large, discrete steps in expenditure. LANs have the ability to be deployed with a smoother cost curve in less severe increments.

Why are network layers important?

Communication networks are often broken into a series of layers, each of which can be defined separately, to enable vendors to develop software and hardware that can work together in the overall network. These layers enable simplicity in development and also in the comprehension of complex networks. In the end, the strategy of using more simplistic network layers allows vastly different kinds of equipment to be able to have connectivity over a common platform or network, using protocols and standards that are applicable to each narrow slice of the network.

How does analog data differ from digital data?

Computers produce digital data that are binary, either on or off. In contrast, telephones produce analog data whose electrical signals are shaped like the sound waves they transfer. Analog data are signals that vary continuously within a range of values (e.g., temperature is analog).

Explain how multicasting works.

Computers wishing to participate in a multicast (e.g., for videoconferencing) send a message to the sending computer or some other computer performing routing along the way using a special type of TCP-level packet called Internet Group Management Protocol (IGMP). Each multicast group is assigned a special Class D IP address to identify the group. Any computer performing routing knows to route all multicast messages with this Class D IP address onto the subnet that contains the requesting computer. The routing computer sets the data link layer address on multicast messages to a matching multicast data link layer address. Each requesting computer must inform its data link layer software to process incoming messages with this multicast data link layer address. When the multicast session ends (e.g., the videoconference is over), the client computer sends another IGMP message to the organizing computer or the computer performing routing to remove it from the multicast group.

What are the differences between connectionless and connection-oriented routing?

Connectionless routing means each packet is treated separately and makes its own way through the network. It is possible that different packets will take different routes through the network depending upon the type of routing used and the amount of traffic. Because packets following different routes may travel at different speeds, they may arrive out of sequence at their destination. The sender's network layer therefore puts a sequence number on each packet, in addition to information about the message stream to which the packet belongs. The network layer must reassemble them in the correct order before passing the message to the application layer. Connection-oriented routing sets up a virtual circuit between the sender and receiver. In this case, a temporary virtual circuit is defined between the sender and receiver. The network layer makes one routing decision when the connection is established, and all packets follow the same route. All packets in the same message arrive at the destination in the same order in which they were sent. In this case, packets only need to contain information about the stream to which it belongs; sequence numbers are not needed, although many connection-oriented protocols include a sequence number to ensure that all packets are actually received. Connection-oriented routing has greater overhead than connectionless routing, because the sender must first "open" the circuit by sending a control packet that instructs all the intervening devices to establish the circuit routing. Likewise, when the transmission is complete, the sender must "close" the circuit. Connection-oriented protocols also tend to have more overhead bits in each packet.

true

Cross-talk occurs when the signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel.

How does cyclical redundancy checking (CRC) work?

Cyclical redundancy check (CRC) adds 8, 16, 24 or 32 bits to the message. With CRC, a message is treated as one long binary number, P. Before transmission, the data link layer (or hardware device) divides P by a fixed binary number, G, resulting in a whole number, Q, and a remainder, R/G. So, P/G = Q + R/G. For example, if P = 58 and G = 8, then Q = 7 and R = 2. G is chosen so that the remainder R will be either 8 bits, 16 bits, 24 bits, or 32 bits. The remainder, R, is appended to the message as the error checking characters before transmission. The receiving hardware divides the received message by the same G, which generates an R. The receiving hardware checks to ascertain whether the received R agrees with the locally generated R. If it does not, the message is assumed to be in error.

true

Cyclical redundancy check is the most popular polynomial error-checking scheme.

Optical media is: a. more likely to suffer from noise than electrical media b. has about the same likelihood of suffering from noise as electrical media c. has about the same likelihood of suffering from noise as coaxial cable d. less likely to suffer from noise than electrical media e. more prone to noise than twisted pair media

Stop-and-wait ARQ uses ___________ type of data flow. a. full simplex b. half complex c. full duplex d. half duplex e. full complex

Which of the following is not an error detection method used in the data link layer? a. parity checking b. cyclic redundancy checking c. CRC-32 d. pulse code checking e. odd parity

Which of the following is true about the data link protocol, SDLC: a. It is a client-server protocol developed by Compaq in 1996. b. It transmits each character independently of one another and includes start and stop bits for each character sent. c. It uses a special bit pattern called a flag at the beginning and end of every frame (or packet). d. It uses a contention media access control protocol and is used in most LANs today. e. It does not have any error detection capabilities.

Which of the following is NOT a layer of a software architecture. a. foundation b. Problem domain c. data management d. data structure e human computer interface

D. data structure

the __ serve(s) as the intermediary between the user and the database a. DBMS b. metadata c. end-user data d. programming language

DBMS

How does DSL (digital subscriber line) work?

DSL services are quite new, and not all common carriers offer them. In general, DSL services have advanced more quickly in the Canada (and Europe, Australia and Asia) than in the United States due to their newer telephone networks from the end offices to the customer. Unlike other services that operate through the telephone network end-to-end from the sender to the receiver, DSL only operates in the local loop from the carrier's end office to the customer's telephone. DSL uses the existing local loop cable, but places one DSL network interface device (called customer premises equipment (CPE)) in the home or business and another one in the common carrier's end office. The end office DSL device is then connected to a high speed digital line from the end office to elsewhere in the carrier's network (often an Internet service provider) using some other service (e.g., T carrier, SMDS).

In which of the following layers of the OSI model would MAC addressing be found? Application Transport Data Link Network

Data Link

Explain the differences among analog data, analog transmission, digital data, and digital transmission.

Data can be transmitted through a circuit in the same form they are produced. Most computers, for example, transmit their data through digital circuits to printers and other attached devices. Likewise, analog voice data can be transmitted through telephone networks in analog form. In general, networks designed primarily to transmit digital computer data tend to use digital transmission, and networks designed primarily to transmit analog voice data tend to use analog transmission (at least for some parts of the transmission).

Data compression and the ISO standard for data compression

Data compression can be used to compress data in order to increase throughput rates in modems V.44 - uses Lempel-Ziv encoding ---Lempel-Ziv encoding produces a dictionary of 2, 3, and 4 character combinations ---every time a repeated character combination occurs, the encoding sends an index to the dictionary, rather than the actual characters ---averages a compression of around 6:1

Why is data compression so useful?

Data compression can increase throughput of data over a communication link literally by compressing the data. A 2:1 compression ratio means that for every two characters in the original signal, only one is needed in the compressed signal (e.g., if the original signal contained 1000 bytes, only 500 would needed in the compressed signal). In 1996, ITU-T revised the V.34 standard to include a higher data rate 33.6 Kbps. This revision is popularly known as V.34+. The faster data rate is accomplished by using a new form of TCM that averages 9.8 bits per symbol (symbol rate remains at 3429).

object-oriented database management system OODBMS

Data management software used to manage data found within an object-oriented database model.

25. ___________ is not a type of digital signaling technique. a. Non-return-to-zero signaling b. Unipolar signaling c. Manchester encoding d. Return-to-zero signaling e. Data rate signaling

Data rate signaling

connectivity

Describes the classification of the relationship between entities. Classifications include 1:1, 1:M, and M:N.

relational model

Developed by E. F. Codd (of IBM) in 1970, it represents a major breakthrough for users and designers because of its conceptual simplicity. The relational model, based on mathematical set theory, represents data as independent relations. Each relation (table) is conceptually represented as a matrix of intersecting rows and columns. The relations are related to each other through the sharing of common entity characteristics (values in columns).

The familiar background static on radios and telephones is called: a. echoes b. intermodulation noise c. impulse noise d. cross-talk e. white noise

The probability of detecting an error, provided that one has occurred, using cyclic redundancy checking is about: a. 75% b. 0% c. exactly 100% d. 50% e. > 99%

_________________ is defined as the total number of information bits divided by the total number of bits in the transmission. a. Asynchronous rate b. Protocol percentage c. Throughput d. Transmission Rate of Information Bits e. Transmission efficiency

Describe the frame layouts for SDLC, Ethernet, and PPP.

Each SDLC frame begins and ends with a special bit pattern, known as the flag. The address field identifies the destination. The length of the address field is usually 8 bits but can be set at 16 bits; all computers on the same network must use the same length. The control field identifies the kind of frame that is being transmitted, either information or supervisory. An information frame is used for the transfer and reception of messages, frame numbering of contiguous frames, and the like. A supervisory frame is used to transmit acknowledgments (ACKs and NAKs). The message field is of variable length and is the user's message. The frame check sequence field is a 16-bit or 32-bit cyclical redundancy checking (CRC) code. For a typical Ethernet packet, the destination address specifies the receiver, while the source address specifies the sender. The length indicates the length in 8-bit bytes of the message portion of the packet. The LLC control and SNAP control are used to pass control information between the sender and receiver. These are often used to indicate the type of network layer protocol the packet contains (e.g., TCP/IP or IPX/SPX as described in Chapter 6). The maximum length of the message is 1492 bytes. The packet ends with a CRC-32 frame check sequence used for error detection. The PPP frame is similar to the SDLC frame. The frame starts with a flag and has a one-byte address. It also contains a control field which is rarely used. The protocol field indicates what type of data is contained. The message portion is variable in length and may be up to 1,500 bytes long. The frame check sequence is either CRC-16 or -32. The frame ends with a flag

What is a subnet and why do networks need them?

Each organization must assign the IP addresses it has received to specific computers on its networks. In general, IP addresses are assigned so that all computers on the same local area network have a similar addresses. For example, suppose a university has just received a set of Class B addresses starting with 128.184.x.x. It is customary to assign all the computers in the same LAN numbers that start with the same first three digits, so the Business School LAN might be assigned 128.184.56.x while the Computer Science LAN might be assigned 128.184.55.x (see Figure 6-8). Likewise, all the other LANs at the university and the backbone network that connects them, would have a different set of numbers. Each of these LANs are called a TCP/IP subnet because they are logically grouped together by IP number. Knowing whether a computer is on your subnet or not it very important for message routing.

T/F: wireless media is more secure

Frequency modulation refers to the changing of the height of the sound wave. TRUE/FALSE

False

T/F: Enterprise resource planning (ERP) applications are small single-function software packages that are inexpensive and easy to install and have only minor problems and fast, easily recognizable benefits.

False

T/F: Frequency modulation refers to the changing of the height of the sound wave

False

T/F: Max has been a project manager for 10 years and is considered one of the best in his department of well qualified IS professionals. The approval committee is considering the approval of a new unique Internet system that could possibly catapult the firm ahead of all of the competition. Buying a packaged system would be the best design strategy.

False

T/F: Michelle would like the opportunity to increase the experience level of her IS staff by having them analyze and design a new web-based distribution system. The skills learned from this project may help with future strategic applications. Since the time period for the project is very flexible and this is a somewhat unique business need, Michelle has decided to use packaged software for this project.

False

T/F: Multiplexing increases the cost of provisioning network circuits.

False

T/F: Non-return to zero is a type of uni-polar signalling

False

T/F: Pirate Adventures, Inc., a company that owns and operates hotels in tropical locations, is interested in replacing the 15-year-old room reservation system in all of its hotels. Custom development would be the best design strategy.

False

T/F: When the timeframe for implementation is short, it is best to consider custom development.

False

The application layer is the seventh layer of the Internet model and specifies the type of connection and the electrical signals that pass through it. True False

False

T/F: Digital transmission produces more errors than analog transmission

False. Digital transmission is basically the 1's and 0's code. However, analog transmission is electronic signals that are sent continuously. But they vary like how there are a bunch of different colors between green and blue.

5 advantages to digital transmission over analog

Fewer errors Higher maximum transmission rates More efficient More secure Simpler to integrate voice, video, and data on same circuit

Discuss three trends in communications and networking.

First, pervasive networking will change how and where we work and with whom we do business. Pervasive networking means that we will have high speed communications networks everywhere, and that virtually any device will be able to communicate with any other device in the world. Prices for these networks will drop and the globalization of world economies will continue to accelerate. Second, the integration of voice, video, and data onto the same networks will greatly simplify networks and enable anyone to access any media at any point. Third, the rise in these pervasive, integrated networks will mean a significant increase the availability of information and new information services. It is likely that application service providers will evolve that act as information utilities.

How many bits (not bytes) are there in a 10 page text document? Hint: There are approximately 350 words on a double-spaced page.

First, some assumptions must be made. Assume each word averages seven letters and there is one space between each word. Next assume we are using 8-bit ASCII. Multiply 350 words by 8 bytes (7 letters plus a space) to get 2,800 bytes per page. Multiply 2,800 by 10 pages to get 28,000 Multiply 28,000 bytes by 8 bits per byte to get 224,000 bits

Flipped bits

What is oversampling?

For voice digitization, one typically samples at twice the highest frequency transmitted, or a minimum of 8,000 times a second. Sampling more frequently than this will improve signal quality. For example, CDs sample at 44,100 times a second and use 16 bits per sample to produce almost error-free music.

true

Forward error correction is commonly used in satellite transmission.

Under what circumstances is forward error-correction desirable?

Forward error correction is commonly used in satellite transmission. A round trip from the Earth station to the satellite and back includes a significant delay. Error rates can fluctuate depending on the condition of equipment, sun spots, or the weather. Indeed, some weather conditions make it impossible to transmit without some errors, making forward error correction essential. Compared to satellite equipment costs, the additional cost of forward error correction is insignificant.

How does forward error correction work? How is it different from other error-correction methods?

Forward error correction uses codes containing sufficient redundancy to prevent errors by detecting and correcting them at the receiving end without retransmission of the original message. The redundancy, or extra bits required, varies with different schemes. It ranges from a small percentage of extra bits to 100 percent redundancy, with the number of error detecting bits roughly equaling the number of data bits.

Describe how data could be transmitted using frequency modulation.

Frequency modulation (FM) (also called frequency shift keying (FSK)), is a modulation technique whereby each 0 or 1 is represented by a number of waves per second (i.e., a different frequency). In this case, the amplitude does not vary. One frequency (i.e., a certain number of waves per second) is defined to be a one, and a different frequency (a different number of waves per second) is defined to be a one.

Which of the following switch features allows for both incoming and outgoing data across physical ports at the same time?

Full-duplex

One commonly used VoIP standard

G.722 wideband audio a version of ADPCM that operates at 64 Kbps - samples at 8,000 per second and produces 8 bits per second

Describe three types of guided media.

Guided media are those in which the message flows through a physical media such as a twisted pair wire, coaxial cable, or fiber optic cable; the media "guides" the signal. One of the most commonly used types of guided media is twisted pair wire, insulated or unshielded twisted pairs (UTP) of wires that can be packed quite close together. Bundles of several thousand wire pairs are placed under city streets and in large buildings. Twisted pair wire is usually twisted to minimize the electromagnetic interference between one pair and any other pair in the bundle. Coaxial cable is another type of commonly used guided media. Coaxial cable has a copper core (the inner conductor) with an outer cylindrical shell for insulation. The outer shield, just under the shell, is the second conductor. Coaxial cables have very little distortion and are less prone to interference, they tend to have low error rates. Fiber optics, is becoming much more widely used for many applications, and its use is continuing to expand. Instead of carrying telecommunication signals in the traditional electrical form, this technology utilizes high-speed streams of light pulses from lasers or LEDs (light emitting diodes) that carry information inside hair-thin strands of glass or plastic called optical fibers.

true

HDLC is very similar to the SDLC synchronous data link protocol.

What are the advantages and disadvantages of host-based networks vs client-server networks?

HOST-BASED: PROS: - centralized security - integrated architecture from single vendor - simpler, centralized installation CONS: - having all processing on host may lead to overload - cost of software and upgrades; expensive infrastructure - terminal totally dependent on server CLIENT-SERVER: PROS: - balanced processing demands - lower cost; inexpensive infrastructure - can use software and hardware from different vendors - scalability CONS: - problems with using software and/or hardware from different vendors - more complex installation or updating (although automated installation software helps greatly in this area)

For what is HTML used?

HTML is the language in which web pages are created. The response body of an HTTP response can be in any format, such as text, Microsoft Word, Adobe PDF, or a host of other formats, but the most commonly used format is HTML. The major parts of HTML are the heading (denoted by the <head> tag) and the body (denoted by the <body> tag) of the response.

How does HTTP use TCP and DNS use UDP?

HTTP at the application layer would pass its message packet with overhead, including the Internet address of the destination, to the transport layer where TCP software would complete packetization at the Transport layer and hand it off to the Network layer. Domain Name Services, the Domain Name Server (aka DNS) is primarily responsible for translating IP Addresses into valid Domain Names and translating valid Domain Names into IP addresses. UDP is a connection-less transport layer protocol. DNS would pass either a Domain Name or an IP address along with its packet(s) to the Transport layer for forwarding to the Network layer to be routed to the destination.

Hamming code

Taken together, the physical and data link layers are called the ____________________. Internet layer Internetwork layer Application layer Hardware layer

Hardware layer

Which of the following is a term used to group together the physical and data link layers? Internetwork layers Software layers Application layers Middleware layers Hardware layers

Hardware layers

Which standards body is responsible for the development of local area network (LAN) standards? ITU-T ISO ANSI IEEE IETF

IEEE

The network layer of the Internet model uses the _____________ protocol to route messages though the network. FTP TCP HTTP IP SMTP

true

If a computer transmits a message containing "ABC" and the destination computer receives "abc" as the message, the message is corrupted.

If you were buying a multiplexer, why would you choose either TDM or FDM? Why?

If buying a multiplexer, you would choose TDM over FDM. In general, TDM is preferred to FDM, because it provides higher data transmission speeds and because TDM multiplexers are cheaper. Time division multiplexing generally is more efficient than frequency division multiplexing, because it does not need guardbands. Guardbands use "space" on the circuit that otherwise could be used to transmit data. It is not uncommon to have time division multiplexers that share a line among 32 different low speed terminals. It is easy to change the number of channels in a time division multiplexer. Time division multiplexers generally are less costly to maintain.

overlapping subtype

In a specialization hierarchy, describes a condition where each entity instance (row) of the supertype can appear in more than one subtype.

disjoint subtype

In a specialization hierarchy, refers to a unique and non-overlapping subtype entity set.

__________can obliterate a group of bits, causing a burst error. a. Cross-talk b. Attenuation c. Impulse noise d. Intermodulation noise e. White noise

Impulse noise

false

Impulse noise is caused by the thermal agitation of electrons.

composite identifier

In ER modeling, a key composed of more than one attribute.

optional participation

In ER modeling, refers to a condition where one entity occurrence does not require a corresponding entity occurrence in a particular relationship.

optional attribute

In ER modeling, refers to an attribute that does not require a value, therefore it can be left empty.

required attribute

In ER modeling, refers to an attribute that must have a value. In other words, it cannot be left empty.

null

In SQL, refers to the absence of an attribute value. Note: A null is not a blank.

burst error

In a _________ , more than one data bit is changed by the error-causing condition. -burst error -data rate shift -Trellis-coded modulation -uniform distribution -amplitude key shift

partial completeness

In a generalization hierarchy, means that not every supertype occurrence is a member of a subtype; that is, there may be some supertype occurrences that are not members of any subtype.

total completeness

In a generalization/specialization hierarchy, a condition in which every supertype occurrence must be a member of at least one subtype.

entity supertype

In a generalization/specialization hierarchy, refers to a generic entity type that contains the common characteristics of entity subtypes.

entity subtype

In a generalization/specialization hierarchy, refers to a subset of an entity supertype where the entity supertype contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype.

true

In a network, the type of errors caused during data transmission can be controlled by the network hardware and software.

repeating group

In a relation, a characteristic describing a group of multiple entries of the same type that exist for a single key attribute occurrence. For example, a car can have multiple colors (top, interior, bottom, trim, and so on).

relation

In a relational database model, an entity set. Relations are implemented as tables. Relations (tables) are related to each other through the sharing of a common entity characteristic (value in a column).

data integrity

In a relational database, refers to a condition in which the data in the database is in compliance with all entity and referential integrity constraints

entity set

In a relational model, refers to a grouping of related entities.

false

In an odd parity-checking scheme, the parity bit is set to make the total number of ones in the byte (including the parity bit) an even number.

Describe how a Web browser and Web server work together to send a Web page to a user.

In order to get a page from the Web, the user must type the Internet Uniform Resource Locator (URL) for the page he or she wants, or click on a link that provides the URL. The URL specifies the Internet address of the Web server and the directory and name of the specific page wanted. In order for the requests from the Web browser to be understood by the Web server, they must use the same standard protocol. The standard protocol for communication between a Web browser and a Web server is Hypertext Transfer Protocol (HTTP).

What is address resolution?

In order to send a message, the sender must be able to translate the application layer address (or server name) of the destination into a network layer address and in turn translate that into a data link layer address. This process is called address resolution. There are many different approaches to address resolution that range from completely decentralized (each computer is responsible for knowing all addresses) to completely centralized (there is one computer that knows all addresses).

subschema

In the network model, the portion of the database "seen" by the application programs that produce the desired information from the data contained within the database.

method

In the object-oriented data model, a named set of instructions to perform an action. Methods represent real-world actions. Methods are invoked through messages.

inheritance

In the object-oriented data model, the ability of an object to inherit the data structure and methods of the classes above it in the class hierarchy.

primary key

In the relational model, an identifier composed of one or more attributes that uniquely identifies a row.

phase modulation

In which type of modulation is a 1 distinguished from a 0 by shifting the direction in which the wave begins?

Two ways to reduce Quantizing error

Increase the number of amplitude levels, which minimizes the differnce between the levels and results in a smoother signal Sample more frequently, which reduces the "length" of each "step", resulting in a smoother signal

homonyms

Indicates the use of the same name to label different attributes; generally should be avoided. Some relational software automatically checks for homonyms and either alerts the user to their existence or automatically makes the appropriate adjustments.

How do information bits differ from overhead bits?

Information bits are those used to convey the user's meaning. Overhead bits are used for purposes such as error checking, and marking the start and end of characters and packets.

Describe how data could be transmitted using a combination of modulation techniques.

It is possible to use amplitude modulation, frequency modulation, and phase modulation techniques on the same circuit. For example, we could combine amplitude modulation with four defined amplitudes (capable of sending two bits) with frequency modulation with four defined frequencies (capable of sending two bits) to enable us to send four bits on the same symbol.

It performs error detection.

5. Which of the following is not a key advantage of digital transmission? a. It permits only low transmission rates. b. It is more efficient. c. It is simpler to integrate voice, video, and data on the same circuit. d. It is more secure. e. It produces fewer errors.

It permits only low transmission rates

Which of the following is NOT a key advantage of digital transmission? It is more efficient. It is simpler to integrate voice, video, and data on the same circuit. It produces fewer errors. It is more secure. It permits only low transmission rates.

It permits only low transmission rates.

It typically involves some waiting because the server has to wait for a response from the polled client or terminal.

It uses a special bit pattern called a flag at the beginning and end of every frame (or packet).

A network engineer is dispatched to an employee office to troubleshoot an issue with the employee's laptop. The employee is unable to connect to local and remote resources. The network engineer flips the laptop's wireless switch on to resolve the issue. At which of the following layers of the OSI model was the issue resolved? Layer 1 Layer 4 Layer 7 Layer 3 Layer 2

Layer 1

The application layer in the TCP/IP model is comparable to which of the following layers in the OSI model? Layer 5 Layer 2 Layer 7 Layer 6

Layer 7

A multi-layer switch operates at which of the following OSI layers? Layers 5 and 6 Layers 1 and 5 Layers 2 and 3 Layers 4 and 5

Layers 2 and 3

The TCP/IP application layer contains which of the following OSI layers? Layers 5,6,7 Layers 1,5,6,7 Layers 4,7 Layer 7

Layers 5,6,7

How do LANs differ from WANs, and BNs?

Local Area Network (LAN) is a group of microcomputers or terminals located in the same general area. Backbone Network (BN) is a large central network that connects most everything on a single company site. Metropolitan Area Network (MAN) encompasses a city or county area. Wide Area Network (WAN) spans cities, states, or national boundaries. Typically, MANs and WANs used leased facilities, while LANs and BNs are often located internally in an organization and used owned facilities.

Which of the following transmission methods is used for network utilizing the 802.3 standard Baseband MAC Broadband DSSS Synchronous

MAC

Which of the following transmission methods is used for network utilizing the 802.3 standard?

MAC

Which of the following refers to a network that spans several buildings that are within 10 miles of each other? LAN MAN BN WAN

MAN

What is middleware and what does it do?

Middleware manages client-server message transfer and shields application software from impacts of hardware changes. Middleware provides standard communication between products of different vendors through translation.

What is a modem?

Modem is an acronym for MOdulator/DEModulator. A modem takes the digital electrical pulses received from a computer, terminal, or microcomputer and converts them into a continuous analog signal that is needed for transmission over an analog voice grade circuit. Modems are either internal (i.e., inside the computer) or external (i.e., connected to the computer by a cable).

false

Most computer networks managed by a host mainframe computer use contention media access control.

Explain why most telephone company circuits are now digital.

Most telephone company circuits are now digital because digital transmission is "better" than analog transmission. Specifically, digital transmission offers several key benefits over analog transmission: - Digital transmission produces fewer errors than analog transmission. Because the transmitted data is binary (only two distinct values), it is easier to detect and correct errors. - Digital transmission is more efficient. Time division multiplexing (TDM) is more efficient than frequency division multiplexing (FDM) because TDM requires no guardbands. TDM is commonly used for digital transmission, while FDM is used for analog transmission. - Digital transmission permits higher maximum transmission rates. Fiber optic cable, for example, is designed for digital transmission. - Digital transmission is more secure because it is easier to encrypt. - Digital transmission is less expensive than analog in many instances. Finally, and most importantly, integrating voice, video and data on the same circuit is far simpler with digital transmission.

business rule

Narrative descriptions of a policy, procedure, or principle within an organization. Examples: A pilot cannot be on duty for more than 10 hours during a 24-hour period. A professor may teach up to four classes during any one semester.

At which of the following layers of the OSI model do packets exist? Session Transport Network Data Link

Network

hierarchical model

No longer a major player in the current database market; important to know, however, because the basic concepts and characteristics form the basis for subsequent database development. This model is based on an "upside-down" tree structure in which each record is called a segment. The top record is the root segment. Each segment has a 1:M relationship to the segment directly below it.

Briefly define noise.

Noise consists of undesirable electrical signals, or, in the instance of fiber optic cable, undesirable light. Noise is typically introduced by equipment or natural disturbances, and it can seriously degrade the performance of a communication circuit. Noise manifests itself as extra bits, missing bits, or bits that have been "flipped," (i.e., changed from 1 to 0 or vice versa).

Analog transmission

Occurs when the signal sent over the transmision media continuously varies from one state to another in a wave-like pattern modems translate digital data from a computer into analog signals to be transmitted over telephone circuits

many-to-many (M:N) relationship

One of three types of relationships (associations among two or more entities) in which one occurrence of an entity is associated with many occurrences of a related entity and one occurrence of the related entity is associated with many occurrences of the first entity.

one-to-one (1:1) relationship

One of three types of relationships (associations among two or more entities) that are used by data models. In a 1:1 relationship, one entity instance is associated with only one instance of the related entity.

one-to-many (1:M) relationship

One of three types of relationships (associations among two or more entities) that are used by data models. In a 1:M relationship, one entity instance is associated with many instances of the related entity.

What is quadrature amplitude modulation (QAM)?

One popular technique is quadrature amplitude modulation (QAM). QAM involves splitting the symbol into eight different phases (three bits) and two different amplitudes (one bit), for a total of 16 different possible values. Thus, one symbol in QAM can represent four bits.

true

One type of forward error correction is the Hamming code.

Simplex transmission

One-way transmission, such as that with radios and TVs

false

Only the sender of a data transmission needs to be concerned about the rules or protocols that govern how it communicates with the receiver

less likely to suffer from noise than electrical media

Optical media is: -more likely to suffer from noise than electrical media -has about the same likelihood of suffering from noise as electrical media -has about the same likelihood of suffering from noise as coaxial cable -less likely to suffer from noise than electrical media -more prone to noise than twisted pair media

true

Point-to-point Protocol is a byte-count-oriented protocol.

________ is the process of sending a signal to a client that gives its permission to transmit or asks it to receive. a. Contention b. Polling c. Pooling d. Carrier sense e. CRC

Polling

What is Quality of Service routing and why is it useful?

Quality of service (QoS) routing is a special type of connection-oriented dynamic routing in which different messages or packets are assigned different priorities. For example, videoconferencing requires fast delivery of packet to ensure that the images and voices appear smooth and continuous; they are very time-dependent, because delays in routing will seriously affect the quality of the service provided. Email can have a low QoS, as it is not critical that it be delivered immediately to the destination.

What is quantizing error?

Quantizing error is the difference between the replicated analog signal and its original form, shown with jagged "steps" rather than the original, smooth flow. Voice transmissions using digitized signals that have a great deal of quantizing error will sound metallic or machinelike to the human ear.

database management system

Refers to the collection of programs that manages the database structure and controls access to the data stored in the database.

EER diagram EERD

Refers to the entity-relationship diagram resulting from the application of extended entity relationship concepts that provide additional semantic content in the ER model.

granularity

Refers to the level of detail represented by the values stored in a table's row. Data stored at their lowest level of granularity are said to be atomic data.

Logical circuit

Refers to the transmission characteristics of the connection

What is routing?

Routing is the process of determining the route or path through the network that a message will travel from the sending computer to the receiving computer. Every computer that performs routing has a routing table developed by the network manager that specifies how messages will travel through the network.

What roles do SMTP, POP, and IMAP play in sending and receiving e-mail on the Internet?

SMTP defines how message transfer agents operate and how they format messages sent to other message transfer agents. SMTP standard covers message transmission between message transfer agents (i.e., mail server to mail server). Post Office Protocol (POP) defines how user agents operate and how messages to and from mail transfer agents are formatted. POP is gradually being replaced by a newer standard called Internet Mail Access Protocol (IMAP). While there are several important technical differences between POP and IMAP, the most noticeable difference is that before a user can read a mail message with a POP user agent, the e-mail message must be copied to the client computer's hard disk and deleted from the mail server. With IMAP, e-mail messages can remain stored on the mail server after they are read.

What feature distinguishes serial mode from parallel mode?

Serial mode is distinguished from parallel mode by the time cycle in which the bits are transmitted. Parallel implies that all bits of a character are transmitted, followed by a time delay, and then all bits of the next character are transmitted, followed by a time delay. Serial implies that characters are sent one bit at a time, with each bit followed by a time delay. Put another way, parallel is character-by-character and serial is bit-by-bit.

How does TCP/IP perform address resolution for network layer addresses?

Server name resolution is the translation of application layer addresses into network layer addresses (e.g., translating an Internet address such as www.cba.uga.edu into an IP address such as 128.192.98.3). This is done using the Domain Name Service (DNS). Throughout the Internet there are a series of computers called name servers that provide DNS services. These name servers run special address databases that store thousands of Internet addresses and their corresponding IP addresses. These name servers are in effect the "directory assistance" computers for the Internet. Any time a computer does not know the IP number for a computer, it sends a message to the name server requesting the IP number. When TCP/IP needs to translate an application layer address into an IP address, it sends a special TCP-level packet to the nearest DNS server. This packet asks the DNS server to send the requesting computer the IP address that matches the Internet address provided. If the DNS server has a matching name in its database, it sends back a special TCP packet with the correct IP address. If that DNS server does not have that Internet address in its database, it will issue the same request to another DNS server elsewhere on the Internet. Once your computer receives an IP address it is stored in a server address table. This way, if you ever need to access the same computer again, your computer does not need to contact a DNS server. Most server address tables are routinely deleted whenever you turn off your computer.

What are three ways of reducing errors and the types of noise they affect?

Shielding (protecting wires by covering them with an insulating coating) is one of the best ways to prevent impulse noise, cross-talk and intermodulation noise. Moving cables away from sources of noise (especially power sources) can also reduce impulse noise cross-talk and intermodulation noise. For impulse noise, this means avoiding lights and heavy machinery. Locating communication cables away from power cables is always a good idea. For cross-talk, this means physically separating the cables from other communication cables. Cross-talk and intermodulation noise is often caused by improper multiplexing. Changing multiplexing techniques (e.g., from FDM to TDM), or changing the frequencies or size of the guardbands in frequency division multiplexing can help. Many types of noise (e.g., echoes, white noise, jitter, harmonic distortion) can be caused by poorly maintained equipment or poor connections and splices among cables. The solution here is obvious: tune the transmission equipment and redo the connections. To avoid attenuation, telephone circuits have repeaters or amplifiers spaced throughout their length.

entity

Something about which someone wants to store data; typically a person, a place, a thing, a concept, or an event.

extended entity relationship model EERM

Sometimes referred to as the enhanced entity relationship model; the result of adding more semantic constructs (entity supertypes, entity subtypes, and entity clustering) to the original entity relationship (ER) model.

extended relational data model ERDM

flags

Special codes implemented by designers to trigger a required response, to alert end users to specified conditions, or to encode values. Flags may be used to prevent nulls by bringing attention to the absence of a value in a table.

Quadrature amplitude modulation (QAM)

Splitting the symbol into eight different phases (3 bits) and two different amplitudes (1 bit) for a total of 16 possible values This 64-QAM can represent 4 bits in one symbol - 256 QAM can represent 8 bits commonly used in digital TV services and cable modem Internet services

Statistical time division multiplexing (STDM)?

Statistical time division multiplexing is the exception to the rule that the capacity of the multiplexed circuit must equal the sum of the circuits it combines. STDM allows more terminals or computers to be connected to a circuit than FDM or TDM. STDM is called statistical because selecting the transmission speed for the multiplexed circuit is based on a statistical analysis of the usage requirements of the circuits to be multiplexed. STDM is like TDM, except that each frame has a terminal address and no blanks are sent.

How is TCP different from UDP?

TCP is a connection-oriented protocol. UDP is a connection-less protocol. What are the differences between connectionless and connection-oriented routing? Connection-oriented routing sets up a virtual circuit between the sender and receiver. In this case, a temporary virtual circuit is defined between the sender and receiver. The network layer makes one routing decision when the connection is established, and all packets follow the same route. All packets in the same message arrive at the destination in the same order in which they were sent. In this case, packets only need to contain information about the stream to which it belongs; sequence numbers are not needed, although many connection-oriented protocols include a sequence number to ensure that all packets are actually received. Connection-oriented routing has greater overhead than connectionless routing, because the sender must first "open" the circuit by sending a control packet that instructs all the intervening devices to establish the circuit routing. Likewise, when the transmission is complete, the sender must "close" the circuit. Connection-oriented protocols also tend to have more overhead bits in each packet. Connectionless routing means each packet is treated separately and makes its own way through the network. It is possible that different packets will take different routes through the network depending upon the type of routing used and the amount of traffic. Because packets following different routes may travel at different speeds, they may arrive out of sequence at their destination. The sender's network layer therefore puts a sequence number on each packet, in addition to information about the message stream to which the packet belongs. The network layer must reassemble them in the correct order before passing the message to the application layer.

What are the parts of TCP/IP and what do they do? Who is the primary user of TCP/IP?

TCP performs packetizing: breaking the data into smaller packets, numbering them, ensuring each packet is reliably delivered, and putting them in the proper order at the destination. IP performs routing and addressing. IP software is used at each of the intervening computers through which the message passes; it is IP that routes the message to the final destination. The TCP software only needs to be active at the sender and the receiver, because TCP is only involved when data comes from or goes to the application layer. TCP/IP is the network layer protocol now used on the Internet. It is also the world's most popular network layer protocol, used by almost 70 percent of all backbone, metropolitan, and wide area networks. TCP/IP is commonly combined with Ethernet.

How does TCP establish a session?

TCP sets up a virtual circuit between the sender and the receiver. The transport layer software sends a special packet (called a SYN, or synchronization characters) to the receiver requesting that a connection be established. The receiver either accepts or rejects the connection, and together, they settle on the packet sizes the connection will use. Once the connection is established, the packets flow between the sender and the receiver, following the same route through the network.

identifiers

The ERM uses identifiers to uniquely identify each entity instance. In the relational model, such identifiers are mapped to primary keys in tables.

How are Internet standards developed?

The Internet Engineering Task Force (IETF; www.ietf.org) sets the standards that govern how much of the Internet will operate. Developing a standard usually takes 1-2 years. Usually, a standard begins as a protocol developed by a vendor. When a protocol is proposed for standardization, IETF forms a working group of technical experts to study it. The working group examines the protocol to identify potential problems and possible extensions and improvements, and then issues a report to IETF. If the report is favorable, the IETF issues a Request for Comment (RFC) that describes the proposed standard and solicits comments from the entire world. Once no additional changes have been identified, it becomes a Proposed Standard. Once at least two vendors have developed software based on it, and it has proven successful in operation, the Proposed Standard is changed to a Draft Standard. This is usually the final specification, although some protocols have been elevated to Internet Standards, which usually signifies a mature standard not likely to change. There is a correlation of IETF RFCs to ISO standards.

half-duplex

The ability to transmit in both directions, but only in one direction at a time is an example of _______________ transmission.

Why has the Internet model replaced the OSI model?

The Internet model is simpler (effectively collapsing the top three layers of the OSI model into a single model) and easier to remember and understand. Further, the ISO OSI Reference Model is the result of a formal standardization process and is technical in its presentation. By contrast, the Internet model is appropriate for those within the networking community with practical needs related to implementing the Internet and networking. However, only a few years ago the Internet model was commonly understood to have only four layers. Today, the transport layer is now separately identified in the Internet model, yielding an important, fifth layer for comprehension. This evolution in presentation may show that at least one technical distinction from the OSI model is now considered practical as the scope, volume of traffic, and complexity of networking (and of the Internet) grows.

What type of routing does a TCP/IP client use? What type of routing does a TCP/IP gateway use? Explain.

The TCP/IP client uses static routing because the client must always point to a single gateway router. The TCP/IP gateway router uses dynamic routing because typically it must process multiple requests for routing beyond the single segment that it physically supports.

bandwidth

The _____________ of a circuit determines a circuit's capacity.

Adaptive differential pulse code modulation (ADPCM)

The alternative used by Instant Messaging and many other applications that provide voice services over low-speed digital circuits Samples voice data at 8,000 times per second and uses same 8 bits per sample that PCM does Difference is that it transmits the *difference* between the current 8 bit value and the previous 8 bit value The slowness of change of voice signals means that they can be represented using only 4 bits

Turnaround time

The amount of time half-duplex communication takes to switch between sending and receiving AKA *retrain time*

Describe the seven layers in the OSI network model and what they do.

The application layer is the application software used by the network user. The presentation layer formats the data for presentation to the user by accommodating different interfaces on different terminals or computers so the application program need not worry about them. The session layer is responsible for initiating, maintaining, and terminating each logical session between end users. The transport layer deals with end-to-end issues, such as procedures for entering and departing from the network, by establishing, maintaining, and terminating logical connections for the transfer of data between the original sender and the final destination of the message. The network layer takes the message generated by the application layer and if necessary, breaks it into several smaller messages. It then addresses the message(s) and determines their route through the network, and records message accounting information before passing it to the data link layer. The data link layer formats the message to indicate where it starts and ends, decides when to transmit it over the physical media, and detects and corrects any errors that occur in transmission. The physical layer is the physical connection between the sender and receiver, including the hardware devices (e.g., computers, terminals, and modems) and physical media (e.g., cables, and satellites).

Describe the five layers in the Internet network model and what they do.

The application layer is the application software used by the network user. The transport layer deals with end-to-end issues, such as procedures for entering and departing from the network, by establishing, maintaining, and terminating logical connections for the transfer of data between the original sender and the final destination of the message. The network layer takes the message generated by the application layer and if necessary, breaks it into several smaller messages. It then addresses the message(s) and determines their route through the network, and records message accounting information before passing it to the data link layer. The data link layer formats the message to indicate where it starts and ends, decides when to transmit it over the physical media, and detects and corrects any errors that occur in transmission. The physical layer is the physical connection between the sender and receiver, including the hardware devices (e.g., computers, terminals, and modems) and physical media (e.g., cables, and satellites).

Explain how a message is transmitted from one computer to another using layers.

The application layer is the application software used by the network user. The transport layer is responsible for obtaining the address of the end user (if needed), breaking a large data transmission into smaller packets (if needed), ensuring that all the packets have been received, eliminating duplicate packets, and performing flow control to ensure that no computer is overwhelmed by the number of messages it receives. The network layer takes the message generated by the application layer and if necessary, breaks it into several smaller messages. It then addresses the message(s) and determines their route through the network, and records message accounting information before passing it to the data link layer. The data link layer formats the message to indicate where it starts and ends, decides when to transmit it over the physical media, and detects and corrects any errors that occur in transmission. The physical layer is the physical connection between the sender and receiver, including the hardware devices (e.g., computers, terminals, and modems) and physical media (e.g., cables, and satellites).

subtype discriminator

The attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.

key attribute

The attribute(s) that form(s) a primary key

Which of the common application architectures for e-mail (two-tier client-server, Web-based) is "best"? Explain.

The best architecture for email can depend on how one wants to use e-mail. If a person wants to be able to access their e-mail from anywhere, then Web-based is best. If the person wants professional backup and storage within an organization, then two-tier client-server is best. If the person wants storage of e-mail strictly under their control and they also want to be able to access their e-mail files off-line when there is a network service interruption, then host-based is best. Employers may choose to use client-server architecture for email access within the organization and Web-based architecture for access to the same system for those times when employees are outside the company (at home, at another business, or on travel).

What benefits and problems does dynamic addressing provide?

The bootp or DHCP server can be configured to assign the same network layer address to the computer each time it requests an address (based on its data link layer address), or it can lease the address to the computer by picking the "next available" network layer address from a list of authorized addresses. Addresses can be leased for as long as the computer is connected to the network or for a specified time limit (e.g., two hours). When the lease expires, the client computer must contact the bootp or DHCP server to get a new address. Address leasing is commonly used by Internet service providers (ISPs) for dial-up users. Dynamic addressing greatly simplifies network management in non-dial-up networks too. With dynamic addressing, address changes need to be done only to the bootp or DHCP server, not each individual computer. The next time each computer connects to the network or whenever the address lease expires, it automatically gets the new address

What is a circuit?

The circuit is the pathway through which the messages travel. It can be made up of a copper wire, although fiber optic cable and wireless transmission are becoming more common. A circuit can also pass across many types of physical facilities such as copper wire or fiber optic cable, but the single end-to-end connection, no matter what the equipment, is referred to as the circuit. There are many devices along the circuit's path that perform special functions such as hubs, switches, routers, and gateways.

What is a client?

The client is the input or output hardware device at the other end of a communication circuit. It typically provides remote users with access to the network and the data and software on the server.

true

The data link layer accepts messages from the network layer and controls the hardware that transmits them.

What does the data link layer do?

The data link layer controls the way messages are sent on the physical media. The data link layer handles three functions: media access control, message delineation, and error control. The data link layer accepts messages from the network layer and controls the hardware that actually transmits them. The data link layer is responsible for getting a message from one computer to another without errors. The data link layer also accepts streams of bits from the physical layer and organizes them into coherent messages that it passes to the network layer.

relational schema

The description of the organization of a relational database as seen by the database administrator.

Bandwidth

The difference between the highest and the lowest frequencies in a band or set of frequencies

Quantizing error

The difference between the smooth flow of a sound wave and the approximated digital representation - produces a metallic sound

false

The distance between repeaters or amplifiers on a telephone circuit is determined by the amount of power gained per unit length of the transmission.

What factors affect transmission speed?

The factors that affect the transmission speed are the number of bits per signal sample and the number of samples per second.

What are three important characteristics of a sound wave?

The first is the height of the wave, called amplitude. Our ears detect amplitude as the loudness or volume of sound. The second characteristic is the length of the wave, usually expressed as the number of waves per second or frequency. Frequency is expressed in hertz (Hz). Our ears detect frequency as the pitch of the sound. Human hearing ranges from about 20 hertz to about 14,000 hertz, although some people can hear up to 20,000 hertz. The third characteristic is the phase, refers to the direction in which the wave begins.

semantic data model

The first of a series of data models that more closely represented the real world, modeling both data and their relationships in a single structure known as an object. The SDM, published in 1981, was developed by M. Hammer and D. McLeod.

first normal form 1NF

The first stage in the normalization process. It describes a relation depicted in tabular format, with no repeating groups and with a primary key identified. All nonkey attributes in the relation are dependent on the primary key.

Which is better, controlled access or contention? Explain.

The key consideration for which is better is throughput -- which approach will permit the largest amount of user data to be transmitted through the network. In most of the 1990s, contention approaches worked better than controlled approaches for small networks that have low usage. In this case, each computer can transmit when necessary, without waiting for permission. In high volume networks, where many computers want to transmit at the same time, the well-controlled circuit originally prevented collisions and delivered better throughput in such networks. Today contention-based systems have been improved to the point where they deliver substantially better throughput and are competitive because of hardware cost considerations.

data managemnt language DML

The language (set of commands) that allows an end user to manipulate the data in the database (SELECT, INSERT, UPDATE, DELETE, COMMIT, and ROLLBACK).

Coding Scheme

The language that computers use to represent data

production database

The main database designed to keep track of the day-to-day operations of a company

What are the major parts of an e-mail message?

The major parts of an e-mail message are: - the header, which lists source and destination e-mail addresses (possibly in text form (e.g., "Susan Smith") as well as the address itself (e.g., [email protected])), date, subject.... - the body, which is the message itself

Compare and contrast unicast, broadcast, and multicast messages.

The most common type of message in a network is the usual transmission between two computers. One computer sends a message to another computer (e.g., a client requesting a Web page). This is called a unicast message. In the situation of a broadcast message, the message is sent to all computers on a specific LAN or subnet. A third type of message called a multicast message is used to send the same message to a group of computers.

What does the network layer do?

The network layer performs three important functions: addressing, routing, and breaking long messages into smaller packets for transmission by the data link layer. The network layer sits between the application layer and the data link layer. The network layer accepts messages from the application layer and formats and addresses them for transmission by the data link layer. The network layer also accepts individual messages from the data link layer and organizes them into coherent messages that it passes to the application layer.

class hierarchy

The organization of classes in a hierarchical tree where each "parent" class is a superclass and each "child" class is a subclass.

conceptual model

The output of the conceptual design process. The conceptual model provides a global view of an entire database. Describes the main data objects, avoiding details.

enterprise database

The overall company data representation, which provides support for present and expected future needs.

database design

The process that yields the description of the database structure. The database design process determines the database components. Database design is the second phase of the database life cycle.

entity integrity

The property of a relational table that guarantees that each entity has a unique value in a primary key and that there are no null values in the primary key.

digital coding

The representation of the character A by the group of 8 bits, 01000001, is an example of:

information

The result of processing raw data to reveal its meaning. consists of transformed data and facilitates decision making.

determination

The role of a key. In the context of a database table, the statement "A determines B" indicates that knowing the value of attribute A means that the value of attribute B can be looked up (determined).

second normal form 2NF

The second stage in the normalization process in which a relation is in 1NF and there are no partial dependencies (dependencies in only part of the primary key).

Describe how mail user agents and message transfer agents work together to transfer mail messages.

The sender of an e-mail uses a user agent (an application layer software package) to write the e-mail message. The user agent sends the message to a mail server that runs a special application layer software package called a message transfer agent. These agents read the envelope and then send the message through the network (possibly through dozens of mail transfer agents) until the message arrives at the receiver's mail server. The mail transfer agent on this server then stores the message in the receiver's mailbox on the server. When the receiver next accesses his or her e-mail, the user agent on his or her client computer contacts the mail transfer agent on the mail server and asks for the contents of the user's mailbox. The mail transfer agent sends the e-mail message to the client computer, which the user reads with the user agent.

What is a server?

The server stores data or software that can be accessed by the clients, or remote users of a hardware input or output device. In client-server computing, several servers may work together over the network to support the business application.

true

The simplest method for error correction is retransmission.

external schema

The specific representation of an external view, that is, the end user's view of the data environment.

For what is HTTP used? What are its major parts?

The standard protocol for communication between a Web browser and a Web server is Hypertext Transfer Protocol (HTTP). An HTTP request from a Web browser to a Web server has three parts. Only the first part is required; the other two are optional. - the request line*, which starts with a command (e.g., GET), provides the URL, and ends with the HTTP version number that the browser understands. - the request header, which contains a variety of optional information such as the Web browser being used (e.g., Internet Explorer), the date, and a userid and password for use if the Web page is password-protected. - the request body, which contains information sent to the server, such as information from a form. The format of an HTTP response from the server to the browser is very similar to the browser request. It has three parts, but only the last part is required; the first two are optional: - the response status, which contains the HTTP version number the server has used, a status code (e.g., 200 means OK, 404 means page not found), and reason phrase (a text description of the status code) - the response header, which contains a variety of optional information such as the Web server being used (e.g., Apache), the date, the exact URL of the page in the response body, and the format used for the body (e.g., HTML) - the response body*, which is the Web page itself.

Pulse code modulation (PCM)

The standard used by the North American telephone network input voice signal is sampled 8,000 times per second (2X the 4000 Hz bandwidth) each time the input voice is sampled, 8 bits are generated, making transmission speed 64 Kbps (8 bits per sample x 8,000 samples per second)

Switch

The switch that connects your local loop the the telephone network it contains a codec that converts the analog signal to a digital signal

Is the bit rate the same as the symbol rate? Explain.

The terms bit rate (i.e., the number bits per second transmitted) and baud rate are used incorrectly much of the time. They often are used interchangeably, but they are not the same. In reality, the network designer or network user is interested in bits per second because it is the bits that are assembled into characters, characters into words and, thus, business information. Because of the confusion over the term baud rate among the general public, ITU-T now recommends the term baud rate be replaced by the term symbol rate. The bit rate and the symbol rate (or baud rate) are the same only when one bit is sent on each symbol. For example, if we use amplitude modulation with two amplitudes, we send one bit on one symbol. Here the bit rate equals the symbol rate. However, if we use QAM, we can send four bits on every symbol; the bit rate would be four times the symbol rate.

Describe the three types of data flows.

The three types of data flows are simplex, half-duplex and full duplex. Simplex is one-way transmission, such as that in radio or TV transmission. Half duplex is two-way transmission, but you can transmit in only one direction at a time. A half duplex communication link is similar to a walkie-talkie link; only one computer can transmit at a time. With full duplex transmission, you can transmit in both directions simultaneously, with no turnaround time.

Some experts argue that MODEMs may soon become obsolete. Do you agree? Why or why not?

The traditional context of MODEM no doubt has become obsolete. We no longer can consider a MODEM a device that connects two computers by merely modulating and demodulating transmission signals over the Public Switched Network at speeds ranging up to 56Kbps. This type of MODEM now must be evaluated in light of newer technologies such as xDSL MODEMs and Cable MODEMs each of which generates, propagates and transmits signals at far greater speeds. In addition we must evaluate the traditional MODEMs as well in light of newer protocols and compression techniques which have greatly improved overall bandwidth and throughput with the traditional types of MODEMs. In short, though many new forms of MODEMs and MODEM supported technology have come in to play, the traditional MODEM continues to be a cost-effective and flexible means of networking if your bandwidth requirements remain under the 56Kbps threshold.

Digital transmission

The transmission of binary electrical or light pulses in that it only has two possible states, a 1 or 0

What does the transport layer do?

The transport layer links application software in the application layer with the network and is responsible for the end-to-end delivery of the message. The transport layer sits between the application layer and the network layer. The transport layer accepts messages from the application layer and packetizes them. Packetizing means to take one outgoing message from the application layer and break it into a set of smaller packets for transmission through the network. Conversely, it also means to take the incoming set of smaller packets form the network layer and reassemble them into one message for the application layer.

false

The two categories of network errors are: lost data and delimited data.

logical link control sublayer

The two sublayers of the data link layer consist of the media access control sublayer and the________ . -logical link control sublayer -network control sublayer -session sublayer -physical sublayer -transport sublayer

Define two fundamental types of errors.

There are two fundamental types of errors: human errors and network errors. Human errors, such as a mistake in typing a number, usually are controlled through the application program. Network errors, such as those that occur during transmission, are controlled by the network hardware and software. There are two categories of network errors: corrupted data (data that have been changed) and lost data.

Which of the following is not true about de jure standards? They can take several years to develop. They are always developed before de facto standards. They can be developed by a government body. They can be developed by an official industry body. One example exists for network layer software (IP).

They are always developed before de facto standards.

Which of the following is not true about de facto standards? They tend to emerge based upon the needs/response of the marketplace. They never evolve into de jure standards. They are generally supported by more than one vendor but de facto standards have no official standing. They are those standards that emerge in the marketplace. They tend not to be developed by an official industry or government body.

They never evolve into de jure standards.

How does a thin client differ from a thick client?

Thick clients support all or most application logic while thin clients support little or no application logic. Development and maintenance costs for more complex thick-client environments can be higher than for thin clients.

Parallel transmission

This is the way the internal transfer of binary data takes place inside a computer Each bit is transferred on its own circuit

what is the throughput of a communication link

Throughput indicates the level of successful packet delivery from one point on the network to another. Dropping packets along the way lowers the throughput and the quality of network connections

splits the communication circuit vertically (with time slots) instead of horizontally

Time (non-statistical) division multiplexing differs from frequency division multiplexing because it:

Time division multiplexing (TDM)?

Time division multiplexing shares a communication circuit among two or more terminals by having them take turns, dividing the circuit "vertically." In TDM, one character is taken from each terminal in turn, transmitted down the circuit, and delivered to the appropriate device at the far end. Time on the circuit is allocated even when data are not be transmitted, so that some capacity is wasted when terminals are idle.

Multiplexing

To break one high-speed physical communication circuit into several lower-speed logical circuits so that many different devices can simultaneously use it but still "think" that they have their own separate circuits

Why are networks set up with multi-layer models? To make them easier to fix and update with technology changes To make them faster to make them simpler and less complex Because vendors could not agree with each other

To make them easier to fix and update with technology changes

Modulation

To represent digital information, a *carrier wave* is sent down the circuit and then *modulated*, or changed in shape to represent a 1 or a 0

How does TCP/IP perform address resolution for data link layer addresses?

To send a message to a computer in its network, a computer must know the correct data link layer address. In this case, the TCP/IP software sends a broadcast message to all computers in its subnet. A broadcast message, as the name suggests, is received and processed by all computers in the same LAN (which is usually designed to match the IP subnet). The message is a specially formatted TCP-level request using Address Resolution Protocol (ARP) that says "Whoever is IP address xxx.xxx.xxx.xxx, please send me your data link layer address." The TCP software in the computer with that IP address then responds with its data link layer address. The sender transmits its message using that data link layer address. The sender also stores the data link layer address in its address table for future use.

true

Token passing is a term that refers to hub polling, in which one computer starts a poll and passes it to the next computer on a multipoint circuit.

Codec

Translates analog voice data into digital form for transmission over digital computer circuits

Modem

Translates the computer's digital data into analog data that can be transmitted through the voice communication circuits, then a modem on the other end translates the analog back to digital

Transmission Rate of Information Bits

Transmission efficiency

What is transmission efficiency?

Transmission efficiency is defined as the total number of information bits (i.e., bits in the message sent by the user) divided by the total bits in transmission (i.e., information bits plus overhead bits).

false

Transmission efficiency refers to the percentage of bits transmitted without errors.

differ widely among media

Transmission speeds:

Full-duplex transimission

Transmit in both directions simultaneously, with no turnaround time

Which of the following OSI model layers is used to order packets which may have arrived out of order? Network Session Presentation Transport

Transport

A walkie-talkie is an example of half-duplex transmission. TRUE/FALSE

True

Amplitude, frequency and phase are all characteristics of a sound wave. TRUE/FALSE

True

At the transport layer in the Internet model, TCP is responsible for breaking large files received from the application layer into smaller messages and opening a connection to a server for transferringthem. True False

True

Data communication standards enable each layer in the sending computer to communicate with its corresponding layer in the receiving computer. True False

True

Due to advances in high speed communication networks, the information lag, or the time it takes for information to be disseminated around the world, has been significantly shortened. True False

True

It is not uncommon for companies to end up spending more money on network management and security tasks than they do on the actual computer equipment itself. True False

True

Of all the media available, fiber optic provides the highest transmission speeds. TRUE/FALSE

True

Signal bandwidth is the difference between the highest and lowest frequencies in a band. TRUE/FALSE

True

T/F: A package is a logical grouping of UML elements.

True

T/F: Data compression can increase the throughput of a communication link

True

T/F: The layer that would include the classes that would interact with middleware applications is the physical architecture layer.

True

T/F: The medium is the physical matter or substance that carries the voice or data transmission.

True

T/F: The purpose of the design phase is to create a blueprint for the new system.

True

The network layer performs the same functions in both the OSI and Internet models and is responsible for routing messages from the source computer to the destination computer. True False

True

True/False: Statistical time division multiplexing does not require the capacity of the circuit to be equal to the sum of the combined circuits.

false

True/False: Another term for stop-and-wait ARQ is sliding window.

False

True/False: Crosstalk occurs when the signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel.

True

True/False: Cyclical redundancy check is one of the most popular polynomial error-checking schemes.

False

True/False: Data transmission errors are typically uniformly distributed in time.

False

True/False: Digital transmission occurs when the signal sent over the transmission media constantly varies among an infinite number of states.

true

True/False: Digital transmission permits higher maximum transmission rates when compared to analog.

False

True/False: Digital transmission produces more errors than analog transmission.

True

True/False: HDLC is very similar to the SDLC synchronous data link protocol.

True

True/False: If a computer transmits a message containing "ABC" and the destination computer receives "abc" as the message, the message is corrupted.

False

True/False: In simplex transmission, the data flows in both directions at the same time

False

True/False: Nonreturn to zero is a type of unipolar signaling

true

True/False: One type of forward error correction is the Hamming code.

true

True/False: One way to reduce quantizing errors is to increase the sampling rate of the analog signal.

What are three of the largest inter-exchange carriers (IXCs) in North America?

Two of the largest inter-exchange carriers (IXCs) in North America are AT&T and Sprint, and the formerly large MCI was acquired in a post bankruptcy merger with Verizon.

Half-duplex transmission

Two-way transmission, but can transmit in only one direction at a time similar to a walkie-talkie computers use *control signals* to negotiate which will send and which will receive data

6 Factors in deciding which type of media to use

Type of network Cost Transmission distance Security Error Rates Transmission speeds

What is the maximum capacity of an analog circuit with a bandwidth of 4,000 Hz using QAM?

Under perfect circumstances, the maximum symbol rate is about 4,000 symbols per second. If we were to use QAM (4 bits per symbol), the maximum data rate would be 4 bits per symbol X 4,000 symbols per second = 16,000 bps.

true

Undesirable stray electrical voltage can cause data communication errors.

Guardbands

Unused portions of a FDM circuit that separate the channels from each other to avoid interference

PAM-5 encoding

Used by 1000Base-T 5 diff voltage levels - 4 to send data and 1 as a control bit --00 = -1.0 V --01 = -0.5 V --10 = +0.5 V --11 = +1.0 V More susceptible to noise (finer differences) so some opt for 100Base-T instead

Compare and contrast the application architecture for videoconferencing with the architecture for e-mail.

Videoconferencing must deliver real-time services demanding high capacity data transfer for both image and voice transmission. Specialized hardware (and even rooms) may be required. E-mail messages (typically without large attachments) are relatively small by comparison, can be received by any Internet-capable computer, and do not have to be consumed in real time.

What is VoIP?

Voice over IP is commonly used to transmit phone conversations over the digital networks. VoIP uses digital phones with built-in codecs to convert analog to digital.

Wavelength division multiplexing (WDM)?

Wavelength division multiplexing is a version of FDM used in fiber optic cables. WDM works by using lasers to transmit different frequencies of light (i.e., colors) through the same fiber optic cable; each channel is assigned a different frequency so that the light generated by one laser does not interfere with the light produced by another. WDM permits up to 40 simultaneous circuits each transmitting up to 10 Gbps, giving a total network capacity in one fiber optic cable of 400 Gbps (i.e., 400 billion bits per second).

serial

When all bits of a character are transferred one after another, the bits are transferred in ___________ mode.

Compare and contrast the three types of addresses used in a network.

When users work with application software, they typically use the application layer address (e.g., entering an Internet address into a browsers, such as www.cba.uga.edu). When a user types an Internet address into a Web browser, the request is passed to the network layer as part of an application layer packet formatted using the HTTP standard. The network layer software translates this application layer address into a network layer address. The network layer protocol used on the Internet is TCP/IP, so this Web address (www.cba.uga.edu) is translated into an TCP/IP address (usually just called an IP address for short) which is four bytes long when using IPv4 (e.g., 128.192.78.5). The network layer then determines the best route through the network to the final destination. Based on this routing, the network layer identifies the data link layer address of the next computer to which the message should be sent. If the data link layer is running Ethernet, then the network layer IP address would be translated into an Ethernet address (e.g., 00-0F-00-81-14-00).

phase

Which of the following is a characteristic of sound waves that can be modulated to convert digital data into analog signals?

CSMA/CD

Which of the following is not a controlled access method of media access control? -Token passing -CSMA/CD -polling -roll call polling -hub polling

prestige value of the type of media

Which of the following is not an important factor to consider when selecting media to be used in a network?

fiber optic cable

Which of the following media can best withstand harsh environmental conditions?

What is a subnet mask?

While it is customary to use the last byte of the IP address to indicate different subnets, it is not required. Any portion of the IP address can be designated as a subnet by using a subnet mask. Every computer in a TCP/IP network is given a subnet mask to enable it to determine which computers are on the same subnet (i.e., LAN) as it is, and which computers are outside of its subnet. The subnet mask is a number that each routing device on a network can use to compare the routing packet to in order to determine if the packet stays in that portion or the network, or should be routed on to the next portion of the network. For example, a network could be configured so that the first two bytes indicated a subnet (e.g., 128.184.x.x) so all computers would be given a subnet mask giving the first two bytes as the subnet indicator. This would mean that a computer with an IP address of 128.184.22.33 would be on the same subnet as 128.184.78.90, and that the message stays within that network. On the other hand, if the subnet comparison shows that the message is not on that particular subnet, then the routing device will move the packets on in their journey.

Some experts argue that thin-client client-server architectures are really host-based architectures in disguise and suffer from the same old problems. Do you agree? Explain.

While thin client have substantially less application logic than thick client, they have sufficient application logic (as, for example, a Web browser possibly with Java applets) to participate in a client-server relationship. The older host-based terminals did not even have this much application logic. While thin-client use today reflects some level of return to a more centralized approach, the client is likely served by multiple servers (and even multiple tiers), rather than a single large host server as in the past. Thus, the two approaches are similar, but not exact, from a technological design perspective.

Describe four types of wireless media.

Wireless media are those in which the message is broadcast through the air, such as radio, infrared, microwave, or satellite. One of the most commonly used forms of wireless media is radio. Radio data transmission uses the same basic principles as standard radio transmission. Each device or computer on the network has a radio receiver/transmitter that uses a specific frequency range that does not interfere with commercial radio stations. The transmitters are very low power, designed to transmit a signal up to 500 feet and are often built into portable or handheld computers. Infrared transmission uses low frequency light waves (below the visible spectrum) to carry the data through the air on a direct line-of-sight path between two points. This technology is similar to the technology used in infrared TV remote controls. It is prone to interference, particularly from heavy rain, smoke, and fog that obscure the light transmission. Infrared is not very common, but it is sometimes used to transmit data from building to building. A microwave is an extremely high frequency radio communication beam that is transmitted over a direct line-of-sight path between any two points. As its name implies, a microwave signal is an extremely short wavelength. Microwave radio transmissions perform the same functions as cables. Similar to visible light waves, microwave signals can be focused into narrow, powerful beams that can be projected over long distances. Transmission via satellite is similar to transmission via microwave except, instead of transmitting to another nearby microwave dish antenna, it transmits to a satellite 22,300 miles in space.

How does decentralized routing differ from centralized routing?

With centralized routing, all routing decisions are made by one central host computer. Centralized routing is used typically only in host-based networks and in this case, routing decisions are rather simple. All computers are connected to the central computer by individual point-to-point circuits, so any message received is simply retransmitted on the point-to-point circuit connected to the destination. Decentralized routing allows all computers in the network make their own routing decisions following a formal routing protocol. In MANs and WANs, the routing table for each computer is developed by its individual network manager. Most decentralized routing protocols are self-adjusting, meaning that they can automatically adapt to changes in the network configuration (e.g., adding and deleting computers and circuits).

false

With contention, a computer does not have to wait before it can transmit. A computer can transmit at anytime.

How does dynamic addressing work?

With dynamic addressing, a server is designated to supply a network layer address to a computer each time the computer connects to the network. This is commonly done for client computers, but usually not done for servers. Instead of providing a network layer address in a configuration file, a special software package is installed on the client that instructs it to contact bootp or DHCP servers using data link layer addresses. This message asks the servers to assign the requesting computer a unique network layer address. The server runs a corresponding bootp or DHCP software package that responds to these requests and sends a message back to the client giving it its network layer address (and its subnet mask).

Under what conditions is media access control unimportant?

With point-to-point full duplex configurations, media access control is unnecessary because there are only two computers on the circuit and full duplex permits either computer to transmit at anytime. There is no media access control

Amplitude Modulation

With respect to converting digital data into analog signals, AM stands for:

true

With roll call polling, a server polls clients in a consecutive, pre-arranged priority list.

Compare and contrast roll-call polling, hub polling (or token passing), and contention.

With roll call polling, the front end processor works consecutively through a list of clients, first polling terminal 1, then terminal 2, and so on, until all are polled. Roll call polling can be modified to select clients in priority so that some get polled more often than others. For example, one could increase the priority of terminal 1 by using a polling sequence such as 1, 2, 3, 1, 4, 5, 1, 6, 7, 1, 8, 9. Hub polling is often used in LAN multipoint configurations (i.e., token ring) that do not have a central host computer. One computer starts the poll and passes it to the next computer on the multipoint circuit, which sends its message and passes the poll to the next. That computer then passes the poll to the next, and so on, until it reaches the first computer, which restarts the process again. Contention is the opposite of controlled access. Computers wait until the circuit is free (i.e., no other computers are transmitting), and then transmit whenever they have data to send. Contention is commonly used in Ethernet local area networks.

How does static routing differ from dynamic routing? When would you use static routing? When would you use dynamic routing?

With static routing, the routing table is developed by the network manager, and changes only when computers are added to or removed from the network. For example, if the computer recognizes that a circuit is broken or unusable (e.g., after the data link layer retry limit has been exceeded without receiving an acknowledgment), the computer will update the routing table to indicate the failed circuit. If an alternate route is available, it will be used for all subsequent messages. Otherwise, messages will be stored until the circuit is repaired. When new computers are added to the network, they announce their presence to the other computers, who automatically add them into their routing tables. Static routing is commonly used in networks that have few routing options. For example, most LANs are connected to the backbone network in only one place. There is only one route from the LAN to the backbone, so static routing is used. Dynamic routing (or adaptive routing) is used when there are multiple routes through a network and it is important to select the best route. Dynamic routing attempts to improve network performance by routing messages over the fastest possible route, away from busy circuits and busy computers. An initial routing table is developed by the network manager, but is continuously updated by the computers themselves to reflect changing network conditions, such as network traffic. Routers can monitor outgoing messages to see how long they take to transmit and how long it takes for the receiving computer to acknowledge them. Based on this monitoring the router can effectuate table updating.

Compare and contrast stop-and-wait ARQ and continuous ARQ.

With stop-and-wait ARQ, the sender stops and waits for a response from the receiver after each message or data packet. After receiving a packet, the receiver sends either an acknowledgment (ACK) if the message was received without error, or a negative acknowledgment (NAK) if the message contained an error. If it is an NAK, the sender resends the previous message. If it is an ACK, the sender continues with the next message. Stop-and-wait ARQ is by definition, a half duplex transmission technique. With continuous ARQ, the sender does not wait for an acknowledgment after sending a message; it immediately sends the next one. While the messages are being transmitted, the sender examines the stream of returning acknowledgments. If it receives an NAK, the sender retransmits the needed messages. Continuous ARQ is by definition a full duplex transmission technique, because both the sender and the receiver are transmitting simultaneously (the sender is sending messages, and the receiver is sending ACKs and NAKs).

How does bipolar signaling differ from unipolar signaling? Why is Manchester encoding more popular than either?

With unipolar signaling, the voltage is always positive or negative (like a dc current). In bipolar signaling, the 1's and 0's vary from a plus voltage to a minus voltage (like an ac current). In general, bipolar signaling experiences fewer errors than unipolar signaling because the signals are more distinct. Manchester encoding is a special type of unipolar signaling in which the signal is changed from a high to low or from low to high in the middle of the signal. A change from high to low is used to represent a 1 (or a 0), while the opposite (a change low to high) is used to represent a 0 (or a 1). Manchester encoding is less susceptible to having errors go undetected, because if there is no transition in mid-signal the receive knows that an error must have occurred.

Can a mail sender use a two-tier architecture to send mail to a receiver using a three-tier architecture? Explain.

Yes. With e-mail, users with the two-tier architecture will use the user agent software to interface with their email server, which will send out web based, SMTP packets to the far end receiver's server computer with mail server software. The server at the far end will issue an IMAP or SMTP packet to the receiver's server computer, which will then arrive at the receiver when they ask for the email with an HTTP request to the web based email application. Thus, a 2-tiered system easily interfaces with a three-tiered architecture over the internet using the appropriate protocols.

Amplitude shift keying

____________ is not a function of a data link protocol. -Media access control -Message delineation -Amplitude shift keying -Indicating when a message starts and stops -Error control

ASCII

____________ is one of the most commonly used coding schemes used in data transmission.

Flipped bits

____________ refers to bits that have been changed, in error, from 1 to 0, or vice versa, in a data transmission. -Contracted bits -Polled bits -Inverse multiplexed bits -Flipped bits -Bit delineation

When a user accesses an application via a web browser on their mobile device, this is referred to as a browser-based approach a native app BYOD Internet Explorer

a browser-based approach

a receiver that detects an error in a message simply asks the sender to retransmit the message until it is received without error

A local area network is: a group of personal computers or terminals located in the same general area and connected by a common cable (communication circuit) so they can exchange information such as a set of rooms, a single building, or a set of well-connected buildings. a large central network that connects other networks in a distance spanning exactly 5 miles. a network spanning a geographical area that usually encompasses a city or county area (3 to 30 miles). a network spanning exactly 10 miles with common carrier circuits. a network spanning a large geographical area (up to 1000s of miles).

a group of personal computers or terminals located in the same general area and connected by a common cable (communication circuit) so they can exchange information such as a set of rooms, a single building, or a set of well-connected buildings.

which of the following is an example of structured data? a. A Web page c. A memo b. An e-mail d. A spreadsheet

a spreadsheet

Coaxial cable

a type of guided media that is quickly disappearing copper core as an inner conductor with an outer cylindrical shell for insulation - outer shield, just under the shell, is the second conductor way more costly than twisted pair cable with no extra benefit

Wavelength division multiplexing (WDM)

a version of FDM used in fiber-optic cables transmit multiple channels using different wavelengths of light Dense WDM (DWDM) is a variant that further increases capacity by adding TDM to WDM

____________ is one of the most commonly used coding schemes used in data transmission. Select one: a. ASCII b. ISDN c. MAU d. ATM e. FDM

a. ASCII

24. Key-value data stores essentially provide a distributed index (primary key) to where a(n) __________________ is stored. a. BLOB (binary, large object) b. field c. entity d. attribute

a. BLOB (binary, large object)

Which of the following is not a key advantage of digital transmission? Select one: a. It permits only low transmission rates. b. It is more efficient. c. It is simpler to integrate voice, video, and data on the same circuit. d. It is more secure. e. It produces fewer errors.

a. It permits only low transmission rates

20. A simple rule to follow when creating problem domain classes and data access and manipulation classes is that there should be ______________. a. One data access and manipulation class for each concrete problem domain class b. Two data access and manipulation classes for each concrete problem domain class c. N data access and manipulation classes for each concrete problem domain class, where N is the number of methods in the problem domain class d. N data access and manipulation classes for each concrete problem domain class, where N is the number of subclasses of the problem domain class e. none of these

a. One data access and manipulation class for each concrete problem domain class

a. about 50% for either even or odd parity

A disadvantage of purchasing packaged software is that the organization may _____. a. accept functionality that is not a perfect fit b. build technical skills and functional knowledge c. make strategic changes during implementation d. remove all risk from the project e. save money on the purchase

a. accept functionality that is not a perfect fit

A(n) ______ matrix can be used to organize the pros and cons of the design alternatives so that the best solution will be chosen in the end. a. alternative b. cost-benefit c. feasibility d. design e. evaluation

a. alternative

The design phase of the SDLC creates a(n) _____. a. blueprint for the future system b. picture of the as-is system c. understanding of who, what, when, and where the future system will be d. understanding of why build the system e. none of the above

a. blueprint for the future system

In a _________ , more than one data bit is changed by the error-causing condition. a. burst error b. data rate shift c. Trellis-coded modulation d. uniform distribution e. amplitude key shift

a. burst error

a. changing multiplexing techniques

With contention: Select one: a. computers wait until the circuit is free before they send data b. the server or front end processor works consecutively through a list of clients to determine who should have access to the media c. the front end processor must wait for a response from the polled client or terminal d. one computer starts the poll and passes it to the next computer on the multipoint circuit

a. computers wait until the circuit is free before they send data

24. Like other problem domain models, the _____________, contracts, and method specifications in class and method design need to be verified and validated. a. constraints b. classes c. behaviors d. associations e. polymorphisms

a. constraints

With __________ ARQ, the sender immediately sends the next message or packet of data. a. continuous b. immediate c. open window d. stop-and-wait e. halt and be recognized (HBR)

a. continuous

9. _____ refers to the level of interdependency or interrelationship among the modules in a system. a. coupling b. cohesion c. connascence d. multiple inheritance e. single inheritance

a. coupling

_________ is an application program function that deals with storing and retrieving data. Select one: a. data storage b. data access logic c. application logic d. presentation logic e. application access storage

a. data storage

Which of the following media is least susceptible to noise? a. fiber optic cable b. coaxial cable c. twisted pair d. unshielded twisted pair e. shielded twisted pair

a. fiber optic cable

19. A mini-table that contains values from one or more columns in a table and the location of the values within the table is called a(n) _____. a. index b. interfile cluster c. intrafile cluster d. raw data calculation e. volumetric

a. index

a. is not very important in point-to-point with full duplex configuration

1. Detailed design is important for two reasons. First, preexisting classes and components need to be understood, organized, and pieced together, and second, _____. a. it is common for the project team to write some code and produce original classes that support the application logic of the system b. it is tempting to jump in without planning c. modular design is outdated d. the SDLC continues to be used instead of a more reliable method of analysis for systems e. top-down modular approaches are an acceptable method of analysis that must be performed during the planning phase

a. it is common for the project team to write some code and produce original classes that support the application logic of the system

5. The basic building block of a system is the _____. a. object b. attribute c. message d. partition e. method

a. object

a. occurs when one circuit picks up signals in another

Which of the following correctly represents order of the seven layers of the OSI model from layer 1 to layer 7? Select one: a. physical, data link, network, transport, session, presentation, application b. data link, physical, network, session, transport, application, presentation c. physical, network, data link, session, transport, application, presentation d. data link, physical, network, transport, session, presentation, application e. physical, data link, network, transport, session, application, presentation

a. physical, data link, network, transport, session, presentation, application

23. Essentially, all OCL expressions are simply a declarative statement that evaluates to either being true or false. If the expression evaluates to true, then the constraint has been _______________. a. satisfied b. executed c. always true d. served as an invariant e. skipped

a. satisfied

about 50% for either even or odd parity

14. Microwave transmission: a. is a type of high frequency radio communication b. requires a clear line-of-sight path c. is typically used for long distance data transmission d. does not require the laying of any cable e. all of the above

all of the above

58. Statistical time division multiplexers differ from time division multiplexers because they: a. can cause time delays when all devices are being used for data transmission at the same time b. take idle time of terminals into account to increase circuit throughput c. use a complicated statistical formula to allocate time slots d. all of the above e. none of the above

all of the above

60. Digital Subscriber Line: a. is a fairly recent approach to provide higher data transmission rates across traditional voice circuits in the local loop b. combines analog transmission and frequency division multiplexing c. involves the use of a customer premises equipment (CPE) d. uses a combination of amplitude and phase modulation e. all of the above

all of the above

32. With respect to converting digital data into analog signals, AM stands for: a. Asynchronous Manchester b. Analog Multimode c. Amplitude Modulation d. Anomaly Multiplexing e. Analytical Mosaic

amplitude modulation

atomic attribute

an attribute that cannot be further subdivided to produce meaningful components. For example, a person's last name attribute cannot be meaningfully subdivided into other name components; therefore, the last name attribute is atomic.

In which layer of the Internet model would the HTTP protocol be used? transport network physical application data link

application

In which layer of the Internet model would the HTTP standard be used? network transport data link physical application

application

a(n) __ might be written by a programmer or it might be created through a DBMS utility program a. query c. database management system b. operating system d. application program

application program

b. 00011011

Which of the following is NOT a controlled access method of media access control? a. Token passing b. CSMA/CD c. polling d. roll call polling e. hub polling

b. CSMA/CD

Which of the following is not a data link layer standard? Select one: a. Ethernet b. HTTP c. Frame Relay d. T1 e. PPP

b. HTTP

b. It is responsible for getting a message from one computer to another (one node to another) without errors.

Which of the following is not an application layer standard? Select one: a. POP b. T1 c. HTML d. HTTP e. IMAP

b. T1

18. The size of a database is determined by the _____. a. amount of raw data in the tables b. amount of raw data in the tables and overhead requirements for the DBMS c. number of instances in the tables d. overhead requirements for the DBMS overhead requirements for the DBMS and number of instances in the tables

b. amount of raw data in the tables and overhead requirements for the DBMS

Errors on a network can occur: a. only on dial-up type of circuits b. because of noise on the line c. only on poorly maintained networks d. only due to Gaussian noise e. only due to lightning strikes

b. because of noise on the line

An advantage of custom development is that the organization can _____. a. accept functionality that is not a perfect fit b. build technical skills and functional knowledge c. install in a short period of time d. remove all risk from the project e. save money on the purchase

b. build technical skills and functional knowledge

10. A class/object should only represent one thing, and a method should only solve a single task. This principle is often referred to as _____. a. coupling b. cohesion c. connascence d. multiple inheritance e. none of these

b. cohesion

12. Which of the following types of interaction coupling is "best?" a. stamp b. data c. content or pathological d. common or global e. control

b. data

15. In order to reduce the number of joins that must be performed in a query and to increase the speed of data access, the data analyst will _____ the physical model. a. cluster b. denormalize c. index d. normalize e. optimize

b. denormalize

When a signal is reflected back to the transmitting equipment, it is called a(n) _________. a. jitter b. echo c. crosstalk d. attenuation e. impulse noise

b. echo

A _________ is a LAN that uses the same technologies as the Internet but is provided to invited users outside the organization who access it over the Internet. Select one: a. MAN b. extranet c. intranet d. BN e. WAN

b. extranet

13. If the data model does not have any repeating fields it is in _____. a. base normal form b. first normal form c. non-normal form d. second normal form e. third normal form

b. first normal form

accurate, relevant, and timely information is the key to __ a. data management b. good decision making c. knowledge d. understanding

b. good decision making

The following are all classic design mistakes EXCEPT _____. a. feature creep b. including design time c. reducing design time d. silver bullet syndrome e. switching tools in mid-project

b. including design time

7. _____ suggests that only the information required to use an object should be available outside the object. a. encapsulation b. information hiding c. polymorphism d. inheritance e. cohesion

b. information hiding

A(n) _____ is the equivalent to a subsystem. a. collaboration b. partition c. layer d. factor e. abstraction

b. partition

6. _____ means having the ability to send the same message to different objects, which can be interpreted differently by different objects. a. encapsulation b. polymorphism c. inheritance d. coupling e. cohesion

b. polymorphism

Time (non-statistical) division multiplexing differs from frequency division multiplexing because it: Select one: a. does not share a communication circuit b. splits the communication circuit vertically (with time slots) instead of horizontally c. increases the wavelength and phase angles of the baseband frequency used for transmission d. moves the baseband of a circuit by shifting it to a higher frequency e. reduces baseband signal velocity more than frequency division multiplexing

b. splits the communication circuit vertically (with time slots) instead of horizontally

18. Fan-out refers to _____. a. the number of attributes a class has b. the number of messages sent by a method c. the number of times a message is sent by a method d. the number of times an attribute is passed from a class e. none of these

b. the number of messages sent by a method

One underlying problem with a host-based network is that: Select one: a. there are economies of scale because all computer resources are centralized b. the server can get overloaded since it must process all messages c. the architecture is relatively simple and works well d. the server is the one point of control which simplifies security e. clients (terminals) do not require sophisticated hardware/software because they do not perform most of the work in this type of architecture

b. the server can et overloaded since it must process all messages

The _________ layer performs error checking which is redundant to some extent with the function of the _________ layer. Select one: a. application, presentation b. transport, data link c. physical, data link d. presentation, transport e. network, physical

b. transport, data link

A _________-tiered architecture uses only two sets of computers: one set of clients and one set of servers. Select one: a. one b. two c. three d. five e. n

b. two

4. A(n) _____ is basically an electronic list of information that is stored on a disk. a. sequential access file b. unordered sequential access file c. ordered sequential access file d. random access file e. transaction file

b. unordered sequential access file

11. A(n) _____ occurs when data are stored redundantly in a database and only some of the instances are updated when a change is needed. a. error b. update anomaly c. data integrity concern d. storage efficiency e. none of these

b. update anomaly

38. The _____________ of a circuit determines a circuit's capacity. a. frequency b. bandwidth c. phase d. amplitude e. loudness

bandwidth

The _____________ of a circuit determines a circuit's capacity.

bandwidth

Errors on a network can occur: a. only on dial-up type of circuits b. because of noise on the line c. only on poorly maintained networks d. only due to Gaussian noise e. only due to lightning strikes

because of noise on the line

_____________ is an effective way to prevent attenuation. Select one: a. Shielding wires b. Adding fluorescent lights c. Adding repeaters or amplifiers to a circuit d. Changing multiplexing techniques e. Shorting a circuit

c. Adding repeaters or amplifiers to a circuit

____________ is NOT a function of a data link protocol. a. Media access control b. Message delineation c. Amplitude shift keying d. Indicating when a message starts and stops e. Error control

c. Amplitude shift keying

17. A class has an attribute in which a range of values has a semantic meaning. This class has _____ connascence. a. Name b. Type or Class c. Convention d. Algorithm e. Position

c. Convention

__________can obliterate a group of bits, causing a burst error. a. Crosstalk b. Attenuation c. Impulse noise d. Intermodulation noise e. Jitter

c. Impulse noise

Which of the following is true about the data link protocol, SDLC: a. It is a client-server protocol developed by Compaq in 1996 b. It is a byte-count-oriented protocol c. It uses a special bit pattern called a flag at the beginning and end of every frame (or packet) d. It uses a contention media access control protocol e. It does not have a problem with transparency

c. It uses a special bit pattern called a flag at the beginning and end of every frame (or packet)

A local area network is: Select one: a. a large central network that connects other networks in a distance spanning exactly 5 miles. b. a network spanning a large geographical area (up to 1000s of miles). c. a group of personal computers or terminals located in the same general area and connected by a common cable (communication circuit) so they can exchange information such as a set of rooms, a single building, or a set of well-connected buildings. d. a network spanning exactly 10 miles with common carrier circuits. e. a network spanning a geographical area that usually encompasses a city or county area (3 to 30 miles).

c. a group of personal computers or terminals located in the same general area and connected by a common cable (communication circuit) so they can exchange information such as a set of rooms, a single building, or a set of well-connected buildings.

The height of a sound wave is called its: Select one: a. frequency b. phase c. amplitude d. bandwidth e. furlong

c. amplitude

A network administrator has received several reports from users of the network that the intranet website on one of company servers is not accessible, but the same users are still able to retrieve their email being stored on the same server. What layer of the Internet model does this problem appear to reside at? Select one: a. network b. transport c. application d. physical e. data link

c. application

In which layer of the Internet model would the HTTP protocol be used? Select one: a. physical b. network c. application d. transport e. data link

c. application

The loss of power a signal suffers as it travels from the transmitting computer to a receiving computer is: a. jitter b. spiking c. attenuation d. intermodulation noise e. echo

c. attenuation

13. Of all of the types of interaction coupling, _____ is the worst. a. stamp b. data c. content or pathological d. common or global e. control

c. content or pathological

Manipulating certain parameters to refine the way features work in a software package is called _____. a. a workaround b. adjustment c. customization d. feature adjustability e. parameterizing

c. customization

With the two-tier client-server architecture, the server is responsible for the ________ logic. Select one: a. application b. presentation c. data access d. session e. physical

c. data access

When an analyst discovers that a set of classes have a similar set of attributes and methods, it may make sense to _____ out the similarities into a separate class. a. refine b. abstract c. factor d. partition e. separate

c. factor

The layer that keeps the user interface implementation separate from the application or problem domain classes is the _____ layer. a. foundation b. system architecture c. human-computer interaction d. data management e. problem domain

c. human-computer interaction

c. is sent by the recipient if the message contains an error

8. The type of database that is most capable of supporting complex data types is _____. a. sequential files b. relational DBMS c. object-oriented DBMS d. object-relational DBMS e. random access files

c. object-oriented DBMS

The direction in which the sound wave begins is known as: Select one: a. amplitude, which our ears detect as loudness b. frequency, which our ears detect as pitch c. phase d. bandwidth e. furlong

c. phase

7. In an object-oriented database, an extent is the equivalent to a(n) _____ in a relational database. a. attribute b. row c. table d. relationship e. unique identifier

c. table

5. SQL operates on _____. a. rows of data at a time b. columns of data at a time c. tables of data at a time d. the entire database e. any of the above

c. tables of data at a time

51. A 56K modem that uses the V.90 standard: a. never has problems with noise on the telephone line b. can recognize an 8-bit digital symbol 8000 times per second c. transmits 56,000 different symbol changes per second at all times d. can be used at full capacity on all North American telephone lines e. currently has 56K transmission rates in both upstream and downstream channels

can recognize a 8-bit digital symbol 8000 times per second

what is frequency modulation

changing the frequency of carrier wave to encode data. one bit is encoded for each carrier wave change (so when the bit changes from 0s to 1s, the frequency lines stay the same height but get closer together)

what is amplitude modulation

changing the height of the wave to encode data. one bit is encoded for each carrier wave change. (so when the bit change from 0s to 1s, the height of the wave changes)

4. Analog data can be transmitted over a digital network by using a special device called a: a. digitizer b. analog converter c. protocol converter d. modem e. codec

codec

Equipment used to transform analog voice signals to digital signals and digital signals to analog signals. voice converter codec modem multiplexer demodulator

codec

the database structure in a DBMS is stored as a __ a. file b. collection of files c. set of key/value pairs d. collection of queries

collection of files

Inverse multiplexing (IMUX)

combines several low-speed circuits to make them appear as one high-speed circuit to the user a common usage is to provide T1 circuits for WANs (T1 combines 24 64 Kbps circuits to transmit at 1.544 Mbps)

59. Inverse multiplexing means: a. combining several low speed circuits to enable them to be transmitted across one high speed circuit b. multiplexing from the terminal to the host, rather than from the host to the terminal c. combining high speed circuits to enable them to be transmitted across one low speed circuit d. inverting the frequencies used for transmission across a low speed circuit for switching to a digital circuit e. multiplexing to a codec, rather than to a modem

combining several low speed circuits to enable them to be transmitted across one high speed circuit

Radio transmission

common form of wireless communication a radio receiver/transmitter uses a specific frequency range that does not interfere with commercial radio stations

The _____ layer addresses the issues involving the persistence of the objects contained in the system. a. foundation b. system architecture c. human-computer interaction d. data management e. problem domain

d. data management

2. A(n) _____ is less expensive and easier for novice users to use, but it does not have the features that are necessary to support mission-critical or large scale systems. a. database b. database management system c. end-user database administrative system d. end-user database management system e. enterprise database management system

d. end-user database management system

25. The constraints and contracts in class and method design models were derived from the ____________ requirements and the problem domain representations. a. business b. regularly c. non-functional d. functional e. reliability

d. functional

Stop-and-wait ARQ uses ___________ type of data flow. a. full simplex b. half complex c. full duplex d. half duplex e. full complex

d. half duplex

There are three methods to create a new system. They are _____. a. buy a package, external vender, external service provider b. develop custom application in-house, external service provider, and external vender c. external service provider, rely on a developer, and external vender d. in-house custom application, buy a package, and external vender e. in-house custom application, external service provider, and external vender

d. in house custom application, buy a package, and external vender

__ is used to reveal the meaning of data

d. information

11. What are the two types of coupling in object-oriented systems? a. interaction, data b. data, inheritance c. data, stamp d. interaction, inheritance e. data, common

d. interaction, inheritance

16. To improve the access speed of a database, similar records in a table are stored together in primary key order. This optimizing access speed process is called _____. a. denormalization b. indexing c. interfile clustering d. intrafile clustering e. volumetrics

d. intrafile clustering

22. There are three different types of constraints typically captured in object-oriented design: preconditions, postconditions, and _____________. a. regular conditions b. guard conditions c. exception handling d. invariants e. contracts

d. invariants

d. less likely to suffer from noise than electrical media

The following are all strengths of a custom development design strategy EXCEPT _____. a. builds technical skills b. greater creativity c. greater flexibility d. lower risk none of the above

d. lower risk

8. In order to get an object to perform a method, a(n) _____ is sent to the object. a. state b. object c. attribute d. message e. instance

d. message

16. Object-oriented systems have three general types of cohesion: _____, _____, and _____. a. method, class, inheritance b. method, generalization/specialization, inheritance c. generalization/specialization, class, object d. method, class, generalization/specialization e. functional, sequential, procedural

d. method, class, generalization/specialization

The _________ layer is responsible for routing of messages from the sender to the final destination. Select one: a. application layer b. resident layer c. data communication layer d. network layer e. physical layer

d. network layer

d. newer version permits jumbo frames

Which of the following is true about the data link protocol, Ethernet (IEEE 802.3)? Select one: a. it is not very popular b. it is a bit-oriented protocol c. it uses block check characters for error detection d. newer version permits jumbo frames e. it uses parity bits for error detection

d. newer version permits jumbo frames

To avoid the classic design mistake of "silver bullet syndrome," the analyst should _____. a. increase the schedule to include learning time b. move proposed changes into future versions c. not switch or upgrade development tools unless there is a compelling need d. not use a design tool that appears too good to be true e. use rapid application development techniques or timeboxing

d. not use a design tool that appears too good to be true

Networks that are designed to connect similar computers that share data and software with each other are called: Select one: a. client/server networks b. host networks c. local area networks d. peer-to-peer networks e. client networks

d. peer-to-peer networks

The ____________ layer of the OSI model is responsible for data format translation. Select one: a. application b. physical c. session d. presentation e. transport

d. presentation

________ is the presentation of information to the user and the acceptance of the user's commands. Select one: a. data storage b. data access logic c. application logic d. presentation logic e. application access storage

d. presentation logic

Which of the following is not a fundamental way to approach the creation of a new information system? a. develop a custom application in-house b. rely on an external vendor to build the system c. purchase a software package and customize it d. rely on end-users to develop it themselves e. all of the above are ways to create new information systems

d. rely on end-users to develop it themselves

12. A data model that does not contain repeating fields and that the data models leads to tables containing fields that are dependent on a whole primary key is in _____ normal form. a. balanced b. first c. primary d. second e. third

d. second

Which of the following is a term used to group together the physical and data link layers? Select one: a. Software layers b. Middleware layers c. Application layers d. Internetwork layers e. Hardware layers

e. Hardware layers

In the model presented by the book, the application layer corresponds to the ________ layer(s) of the OSI model. Select one: a. data link and network b. application and presentation c. network, transport and presentation d. session, presentation and application e. application layer

d. session, presentation and application

d. stop and wait

6. Which of the following is NOT a characteristic of current object-relational databases? a. storage of objects in the relational table structure b. good support for typical data management operations c. SQL support d. support for inheritance e. all of these are characteristics of object-relational databases

d. support for inheritance

The process of building new systems by combining packaged software, existing legacy systems, and new software written to integrate everything together is called _____. a. customization b. formal methodology c. outsourcing d. systems integration e. workaround

d. systems integration

The following are all strengths of a packaged software design strategy EXCEPT _____. a. it may be bought and installed in a short time b. many business needs are not unique c. the package is already tested and generally proven to work d. there is an exact match of functionality to requirements e. none of the above

d. this is an exact match of functionality to requirements

The fourth layer of the OSI model is called the __________ layer. Select one: a. session b. data link c. presentation d. transport e. network

d. transport

half-duplex transmission

data flows both ways, but only in one direction at a time (ex. CB radio, walkie-talkie)

full-duplex transmission

data flows in both directions at the same time (ex. telephone)

__ exists when different versions of the same data appear in different places a. Data inconsistency c. Better data integration b. Data consistency d. Improved decision making

data inconsistency

___________ is not a type of digital signalling technique non-return-to-zero signalling unipolar signaling return-to-zero signaling data rate signaling manchester encoding

data rate signaling

what is analog data and how does it compare to moving water

data that is represented in a physical way. it can be converted to digital form. example would be a magnetic tape of a VCR cassette. analog data is the actual water surface in motion that we can physically sense. a digital format would convert the physical movement of the water into data sets to simulate these properties

the __ structure is quite different from that of an operational or transactional database a. data warehouse c. enterprise database b. workgroup database d. distributed database

data warehouse

the phrase __ refers to an organization of components that define and regulate the collection, storage, management and use of data within a database environment (a)database management system (c)management system (b)database management (d)database system

database system

18. Transmission speeds: a. are the same among all media b. are not a factor in selecting a media because all media have more than enough speed to serve current communication demands c. are a constant, 56Kbps, for all media types d. differ widely among media e. always have a direct correlation with security

differ widely among media

3. In general, networks designed to transmit primarily computer data are likely to be ________, while networks designed to transmit voice data are likely to be ________. a. slow, fast b. level 1, level 2 c. numeric, musical d. direct, indirect e. digital, analog

digital and analog

22. The representation of the character A by the group of 8 bits, 10000001, is an example of: a. digital coding b. phase modulation c. binary modulation d. analog transmission e. pitch variation

digital coding

The representation of the character A by the group of 8 bits, 01000001, is an example of:

digital coding

6. In the future, most long distance transmission (voice, data, and video) will be sent using: a. analog transmission b. digital transmission c. unipolar signaling d. analog transmission e. infrared linking

digital transmission

__________ refers to the spreading of the signal that different parts of the signal arrive at different times at the destination. attenuation insulation turnaround time propagation delay dispersion

dispersion

___________ refers to the spreading of the signal that different parts of the signal arrive at different times at the destination.

dispersion

a __ database supports data distributed across several different sites a. single-user c. centralized b. multiuser d. distributed

distributed

Frequency division multiplexing (FDM)

dividing the circuit "horizontally" so that many signals can travel a single communication circuit simultaneously divided into channels transmitting at different frequencies - each channel is separate logical circuit

27. Which type of digital signaling would experience fewer errors because it has more distinct signals? a. unipolar b. serial c. double current d. attenuation e. Huffman encoding signal

double current

61. ___________ is one way that data rates over traditional telephone lines can be increased dramatically. a. SONET b. T-carrier services c. CSU/DSU d. ATM e. DSL

dsl

The probability of detecting an error, provided that one has occurred, using cyclic redundancy checking is about: a. 75% b. 0% c. exactly 100% d. 50% e. > 99%

e. > 99%

Which of the following is not true about de facto standards? Select one: a. They tend to emerge based upon the needs/response of the marketplace. b. They are generally supported by more than one vendor but de facto standards have no official standing. c. They are those standards that emerge in the marketplace. d. They tend not to be developed by an official industry or government body. e. They never evolve into de jure standards.

e. They never evolve into de jure standards.

e. Transmission efficiency

21. Constraints can be written in either a natural language, a semiformal language, or a formal language such as ________________. a. UML b. Structured English c. Use case diagrams d. English e. UML's Object Constraints Language

e. UML's Object Constraints Language

17. _____ is the process of estimating the amount of data that the hardware will need to support, so that the server hardware specifications are sufficient for the project's needs. a. Indexing b. Interfile clustering c. Intrafile clustering d. Raw data calculating e. Volumetrics

e. Volumetrics

The decision on which design strategy to use depends on _____. a. how unique the business need is b. the expertise of the project manager c. the urgency of the project d. the amount of in-house experience e. all of the above

e. all of the above

2. In an object-oriented system, changes can take place at the following level of abstraction. a. variable b. method c. class/object d. cluster (examples: partition, package) e. all of these

e. all of these

15. When a method of one object refers to the inside hidden parts of another object, these methods are exhibiting _____ coupling. a. data b. stamp c. control d. common or global e. content or pathological

e. content or pathological

3. A(n) _____ can support large volumes of data and support applications that run an entire company. a. database b. database management system c. end-user database administrative system d. end-user database management system e. enterprise database management system

e. enterprise database management system

1. Data may be stored in the following formats _____. a. databases b. entities c. entities and files d. files e. files and databases

e. files and databases

The _____ layer contains, among other things, the classes that represent the fundamental data types. a. problem domain b. system architecture c. human-computer interaction d. data management e. foundation

e. foundation

e. is also known as start-stop transmission

e. is used to transmit a "frame" or "packet" of data at a time

4. In terms of levels of abstraction, which of the following is at the lowest level relative to the rest? a. system b. partition/package c. library d. class/object e. method

e. method

The _____ layer addresses how the software will execute on specific computers and networks. a. foundation b. system architecture c. human-computer interaction d. data management e. problem domain

e. problem domain

Which is not a function of the physical layer: Select one: a. specifying the type of connection and type of signals, waves or pulses that pass through it. b. providing the physical connection between sender and receiver. c. defining the rules by which one and zeroes are transmitted. d. transmission of bits. e. providing error-free transmission of data.

e. providing error-free transmission of data.

9. The process of ensuring that values linking tables together through the primary and foreign keys are valid and correctly synchronized is _____. a. hierarchical integrity b. primary integrity c. table integrity d. referential unity e. referential integrity

e. referential integrity

An advantage of purchasing packaged software is that the organization can _____. a. accept functionality that is not a perfect fit b. build technical skills and functional knowledge c. have developers climb the knowledge ladder d. make strategic changes during implementation e. save money on the purchase

e. save money on the purchase

10. A relational database may be optimized for _____. a. data type and storage efficiency b. relational type c. speed of access d. storage efficiency e. storage efficiency and speed of access

e. storage efficiency and speed of access

e. the physical and the network layers

14. If the logical data model contains fields that depend on another non-primary key field, then it is in violation of the rules of _____. a. base normal form b. first normal form c. non-normal form d. second normal form e. third normal form

e. third normal form

To avoid the classic design mistake of "feature creep," the analyst should _____. a. not switch or upgrade unless there is a compelling need for specific features b. increase the schedule to include learning time c. move proposed changes into future versions d. not use a design tool that appears too good to be true e. use rapid application development techniques or timeboxing

e. use rapid application development techniques or timeboxing

To avoid the classic design mistake of "reducing the design time," the analyst should _____. a. increase the schedule to include learning time b. move proposed changes into future versions c. not switch or upgrade unless there is a compelling need for specific features d. not use a design tool that appears too good to be true e. use timeboxing

e. use time boxing

The familiar background static on radios and telephones is called: a. echoes b. intermodulation noise c. line outages d. cross-talk e. white noise

e. white noise

each character is transmitted independently of all other characters

The primary reason for networking standards is to: lock customers into buying network components from one vendor ensure that all network components of a particular network can be provided by only one vendor make it more difficult to develop hardware and software that link different networks simplify cost accounting for networks ensure that hardware and software produced by different vendors can work together

ensure that hardware and software produced by different vendors can work together

a(n) __ database is used by an organization and supports many users across many departments a. desktop c. enterprise b. workgroup d. transactional

enterprise

T/F: A physical circuit refers to the transmission characteristics of the connection, such as the speed at which data is being sent through the connection

false

T/F: Based on the TIA/EIA 568-B structured cabling standard, the cabling that runs from the telecommunications closet to each work area is called backbone cabling

false

T/F: Custom development of software is usually the best strategy for common business needs, particularly when the business need is not unique and does not have special requirements.

false

T/F: Digital transmission occurs when the signal sent over the transmission media constantly varies among an infinite number of states.

false

T/F: Multimode fiber is capable of longer transmission distances than single mode fiber.

false

T/F: fiber optic cable can only be used on LANS

false

a query language is a procedural language

false

an operational database is sometimes referred to as an enterprise database

false

corporations use only structured data

false

data and information are essentially the same thing

false

database programming language receive all application requests and translate them into the complex operations required to fulfill those requests

false

information implies familiarity, awareness, and understanding knowledge as it applies to an environment

false

one advantage of a database over previous data management approaches is that the database system is considerably less complex

false

one disadvantage of the DBMS is that it increases the risk of data security breaches

false

structural dependence exists when it is possible to make changes in the file structure without affecting the application program's ability to access the data

false

the DBMS reveals much of the database's internal complexity to the application programs and users

false

Which of the following is the most secure wired media? shielded twisted pair coaxial cable fiber optic cable unshielded twisted pair infared

fiber optic

12. Which of the following media can best withstand harsh environmental conditions? a. shielded twisted pair b. unshielded twisted pair c. Cat 5 twisted pair d. coaxial cable e. fiber optic cable

fiber optic cable

Which of the following media has the lowest error rates and the highest transmission speeds? infrared unshielded twisted pair coaxial cable fiber optic cable shielded twisted pair

fiber optic cable

Which of the following media is least susceptible to noise? a. fiber optic cable b. coaxial cable c. twisted pair d. unshielded twisted pair e. shielded twisted pair

fiber optic cable

a __ is a character or group of characters that has a specific meaning (a)database (c)column (b)field (d)file

field

a __ is a collection of related records (a)database (c)column (b)field (d)file

file

56. Which of the following types of multiplexing is least efficient for data transmission? a. frequency division multiplexing b. statistical time division multiplexing c. statistical frequency division multiplexing d. time division multiplexing e. wave division multiplexing

frequency divison multiplexing

55. ________________ separate channels to reduce interference between channels in frequency division multiplexing. a. Channel blockers b. Statistical dividers c. Attenuators d. Guardbands e. Adaptive differential processors

guardbands

FDM use ____________ to make a number of smaller channels

guardbands

8. The two basic types of media are: a. statistical and frequency b. guided and wireless (radiated) c. local and wide area d. attenuator and Gaussian e. duplexed and non-duplexed

guided and wireless (radiated)

The two basic types of media are: guided and wireless (radiated) attenuator and Gaussian statistical and frequency duplexed and non-duplexed local and wide area

guided and wireless (radiated)

What are the two basic types of media

guided and wireless (radiated)

Stop-and-wait ARQ uses ___________ type of data flow. a. full simplex b. half complex c. full duplex d. half duplex e. full complex

half duplex

The ability to transmit in both directions, but only in one direction at a time is an example of ___________ transmission. full-duplex analog simplex half-duplex digital

half-duplex

47. When V.34 modems initially connect, they must go through a ____________ sequence to test the circuit and determine the optimum combination of symbol rate and modulation technique that will produce the highest throughput. a. frequency division b. wave division c. handshaking d. Trellis-coded modulation e. point of presence

handshaking

17. Which of the following media is the least secure? a. coaxial cable b. unshielded twisted pair c. shielded twisted pair d. fiber optic cable e. infrared

infarared

In communication protocols, _________ are used to convey the user's meaning. a. information bits b. overhead bits c. stop bits d. start bits e. flag bits

information bits

Twisted pair cable

insulated pairs of wires that can be packed quite close together the wires are usually twisted to minimize the electromagnetic interference between one pair and any other pair in the bundle

what is IDF (page 267)

intermediate distribution frame (it is the telecommunications room). it is where all horizontal runs from all the work areas come together. This means that it is a per-floor thing. All of the IDF connect to the main frame. that is called the MDF

intermodulation noise

A(n) _________ is a LAN that uses the same technologies as the Internet but is open to only those inside the organization. WAN BN extranet MAN intranet

intranet

is not very important in point-to-point with full duplex configuration

is sent by the recipient if the message contains an error

The American National Standards Institute: sets the standards that govern how much of the Internet will operate is an agency that develops federal information processing standards for the federal government makes technical recommendations about global telephone rates is a professional society in the U.S. whose standards committees focus on local area network standards is the coordinating organization for the United Statesâ€™ national system of standards

is the coordinating organization for the United Statesâ€™ national system of standards

is used to transmit a "frame" or "packet" of data at a time

it is commonly used in WANs

what is quantizing error and how does the number of samples taken affect it?

it is the difference between the original analog signal and the replicated but approximated digital signal produced through PAM. the more samples taken in time, the less quantizing error. This is because PAM takes a wave and converts it into tiny sections and assigned it a binary number. The more tiny sections per wave, the more accurate a representation when the sections are put back together. think about how a higher-def TV is clearer because it has more pixels

Which of the following is not a key advantage of digital transmission? -it is more efficient -it permits only low transmission rates -it is simpler to integrate voice video and data on the same circuit -it produces fewer errors -it is more secure

it permits only low transmission rates

the organization of the data within the folders in a manual file system was determined by __ a. the date of creation c.the title of the documents in the folder b.its expected used d.t he data processing specialist

its expected use

less likely to suffer from noise than electrical media

logical link control sublayer

__ provide(s) a description of the data characteristics and the set of relationships that link the data found within the database a. Queries b. End-user data c. Metadata d. Information

metadata

13. __________ is a line-of-sight type of wireless media. a. coaxial cable b. microwave c. radio d. twisted pair e. fiber optic

microwave

9. Which of the following would be considered a type of wireless media? a. unshielded twisted pair b. shielded twisted pair c. coaxial cable d. microwave e. fiber optics

microwave

45. Which statement is false about modems? a. modems are usually used in pairs (2 at a time) b. a receiving modem demodulates and a sending modem modulates c. most modems support several modem standards so that they can communicate with a variety of modems d. modems may operate at a lower speed that that for which they are rated, especially if they detect noise in the communication line e. modems must always be internal to the computer

modems must always be internal to the computer

__________ refers to changing the shape of the sound wave in different ways to represent a 1 or a 0. modulation sampling digitizing shaping demodulation

modulation

44. The acronym, Modem, stands for _________________. a. multiplexing/demultiplexing b. more/demote c. Mode-M technique d. modulator/demodulator e. Mod emulation technique

modulator/demodulator

what is a coaxial cable mostly used for and how does it compare to TP wires?

mostly used for cable TV and internet cable. less prone to interference than TP but more expensive so it's quickly disapearing

10. The earliest type of fiber optic systems were: a. Graded index multimode b. Attenuated c. Multimode d. Single mode e. Step mode

multimode

52. A(n) ___________ divides one high-speed communication circuit into several lower speed circuits for the primary reason of saving communication line costs. a. transponder b. multiplexer c. inverse multiplexer d. codec e. intelligent terminal

multiplexer

a workgroup database is a(n) __ database a. single-user c. enterprise b. multiuser d. distributed

multiuser

At which layer of the TCP/IP model would cabling exist? Internet application transport network interface

network interface

newer version permits jumbo frames

baud rate

number of symbols transmitted per second. so symbol/seconds

occurs when one circuit picks up signals in another

Cross-talk occurs when ___________

one circuit picks up signals in another

54. Frequency division multiplexing: a. operates by statistically time slicing the signal b. operates by dividing the signal into different frequencies c. uses a codec that divides signals into different channels d. operates by time slicing the signal e. operates by light dividing the signal

operates by dividing the signal into different frequencies

a(n) __ database is designed to support a company's day-to-day operations a. desktop c. enterprise b. workgroup d. transactional

operational

most decision-support data are based on historical data obtained from __ a. operational databases c. enterprise databases b. data warehouses d. workgroup databases

operational databases

__ relates to the activities that make the database perform more efficiently in terms of storage and access speed (a)Performance tuning (c)Query access (b)Database design (d)Database management

performance tuning

28. Which of the following is a characteristic of sound waves that can be modulated to convert digital data into analog signals? a. phase b. attenuation c. bipolar d. bandwidth e. codec

phase

29. The direction in which the sound wave begins is known as: a. amplitude, which our ears detect as loudness b. frequency, which our ears detect as pitch c. phase d. bandwidth e. furlong

phase

Which of the following is a characteristic of sound waves that can be modulated to convert digital data into analog signals attenuation bipolar phase bandwidth codec

phase

33. In which type of modulation is a 1 distinguished from a 0 by shifting the direction in which the wave begins? a. bandwidth modulation b. amplitude modulation c. frequency modulation d. phase modulation e. codec modulation

phase modulation

1. Data is physically transmitted from one computer or terminal to another in the ________ layer. a. physical b. transport c. application d. terminal e. data link

physical

Data is actually transmitted from one computer or terminal to another in the ________ layer. physical data link application terminal transport

physical

Data is physically transmitted from one computer or terminal to another in the ________ layer.

physical

Which of the following correctly represents order of the seven layers of the OSI model from layer 1 to layer 7? physical, network, data link, session, transport, application, presentation physical, data link, network, transport, session, application, presentation data link, physical, network, transport, session, presentation, application data link, physical, network, session, transport, application, presentation physical, data link, network, transport, session, presentation, application

physical, data link, network, transport, session, presentation, application

physically separating the cables from other communication cables

16. Which of the following is not an important factor to consider when selecting media to be used in a network? a. prestige value of the type of media b. type of network c. cost d. transmission distance e. security

prestige value of the type of media

A(n) _____________ is a set of rules that determine what a layer would do and provides a clearly defined set of messages that software at the layer needs to understand. regulation policy protocol specification agreement

protocol

Which of the following is not a function of the data link layer? controlling the physical layer by determining when to transmit formatting the message by indicating where messages start and end, and which part is the address detecting and correcting any errors that have occurred in the transmission of the message specifying the type of connection, and the electrical signals, radio waves, or light pulses that pass through it deciding when to transmit messages over the media

specifying the type of connection, and the electrical signals, radio waves, or light pulses that pass through it

Another term for impulse noise is: a. Gaussian noise b. spikes c. attenuation d. cross-talk e. intermodulation noise

spikes

The primary source of error in data communications is: a. echoes b. intermodulation noise c. spikes d. attenuation e. cross-talk

spikes

a. does not share a communication circuit b. splits the communication circuit vertically (with time slots) instead of horizontally c. increases the wavelength and phase angles of the baseband frequency used for transmission d. moves the baseband of a circuit by shifting it to a higher frequency e. reduces baseband signal velocity more than frequency division multiplexing

splits the communication circuit vertically instead of horizontally

stop and wait

The function of the file server is to : store HTML documents for an Internet or intranet web site. store data and software programs that can be used by client computers on the network. coordinate the communication of client and servers on the network. transfer e-mail messages to other servers on the network. manage all printing requests from clients on the network.

store data and software programs that can be used by client computers on the network.

data dictionary

stores metadata. contains the data definition as well as its characteristics and relationships. may also include data that are external to the DBMS.

Which of the following types of cables would be used to connect a hub to a patch panel T1 Crossover cable Rollover cable Crossover cable Straight-through cable

straight-through cable

__ data are the result of formatting to facilitate storage, use and generation of information a. Structured c. Unstructured b. Semistructured d. Historical

structured

37. __________ is a unit of signaling speed that indicates how often the signal changes on a communication circuit. a. bits per second rate b. phase rate c. symbol rate d. attenuation rate e. trellis rate

symbol rate

_______ is not a form of modulation used to transform digital data into analog signals amplitude modulation amplitude shift keying synchronous time division frequency modulation phase modulation

synchronous time division

______________ is NOT a form of modulation used to transform digital data into analog signals. amplitude modulation phase modulation amplitude shift keying frequency modulation synchronous time division

synchronous time division

31. _____________ is not a form of modulation used to transform digital data into analog signals. a. synchronous time division b. amplitude shift keying c. amplitude modulation d. frequency modulation e. phase modulation

synchronous time divison

The room that contains the cable termination points and the distribution frames is referred to as:

telecommunications closet

TP wires (Twisted Pair) are commonly used for what two things?

telephones and LANS

Circuit configuration

the basic physical layout of the circuit

42. Which of the following statements is true? a. the longer the distance of a telephone wire between sender and recipient, the lower the bandwidth across that wire b. the shorter the distance of a telephone wire between sender and recipient, the lower the bandwidth across that wire c. bandwidth is constant across any wire, therefore distance is not relevant d. the longer the distance of a telephone wire between sender and recipient, the higher the bandwidth across that wire e. bandwidth is not a term that can be used when discussing telephone transmissions

the longer the distance of a telephone wire between sender and recipient, the lower the bandwidth across that wire

Symbol

the pattern of electricity, light, or radio wave that is used to represent a 0 and a 1

the physical and the network layers

During the 1990s, there was intense competition between two technologies (10 Mbps Ethernet and 16 Mbps token ring) for the LAN market. Ethernet was promoted by a consortium of vendors while token ring was primarily an IBM product, even though it was standardized. Ethernet won, and no one talks about token ring anymore. Token ring used a hub-polling-based approach. Outline a number of reasons why Ethernet might have won. Hint: the reasons were both technical and business.

the reasons were both technical and business.

TCM stands for: a. Tandem Control Microprocessor, a hardware feature of front end processors used to manage and control data communications b. Telephone Call Manager, a software package to monitor and report on telephone usage c. Trellis coded modulation, a technique that combines phase modulation and amplitude modulation d. Threaded Code Messaging, a data communications transmission technique in which all redundant bits are stripped before sending and replaced upon receipt of the message e. True Calling Measures, one telephone company's method for changing customers

trellis coded modulation: a technique that combines phase modulation and amplitude modulation

T/F: Frequency is the number of cycles per second and is expressed in Hertz

true

T/F: Radio data transmission requires that each device has a radio receiver/transmitter and uses a specific frequency.

true

T/F: Time division multiplexing is more efficient that frequency division multiplexing because the guardbands used in the frequency division multiplexing or not needed.

true

T/F: data compression can increase the throughput of a communication link

true

a data warehouse can store data derived from many sources

true

data constitute the building blocks of information

true

data processing can be as simple as organizing data to reveal patterns

true

__ data exist in a format that does not lend itself to processing that yields information a. Structured c. Unstructured b. Semistructured d. Historical

unstructured

__ data exist in the format in which they were collected a. Structured c. Unstructured b. Semistructured d. Historical

unstructured

53. The type of multiplexer that divides the circuit horizontally into different light frequencies that are transmitted simultaneously across many channels is a. wave division multiplexer b. time division multiplexer c. statistical time division multiplexer d. frequency division multiplexer e. statistical frequency division multiplexer

wave division multiplexer

The familiar background static on radios and telephones is called: a. echoes b. intermodulation noise c. impulse noise d. cross-talk e. white noise

white noise

work better than contention approaches for large networks that have high usage

a(n) __ database supports a relatively small number of users (usually fewer than 50) or a specific department within an organization a. desktop c. enterprise b. workgroup d. transactional

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