Data Communications Midterm
____ is a 7-bit code allowing 128 possible combinations of textual symbols.
ASCII
What are the functions performed by a network operating system?
Allows users to share resources Provides password protection Networks administrators with services that help them control access to network resources as well as use and administer the network. Allow network administrators to configure network devices like routers, switches, and firewalls Allow network administrators to manage and segment network traffic for increased performance and security.
Typically, impulse noise is a(n) ____ burst of energy.
Analog
The _________________________ is the usual CRC version used for Ethernet.
CRC-32
Unlike CSMA/CD, ____________________ is a contention-based medium access control protocol that is still used on today's LANs.
CSMA/CA
____ noise that happens with twisted pair wires, such as an Ethernet cable, can be electrical.
Crosstalk
A local area network is only as strong as its strongest link.
False
According to a famous communications theorem created by Nyquist, the sampling rate using pulse code modulation must be at least three times the highest frequency of the original analog waveform.
False
Coaxial cable connections are more secure than LED fiber-optic connections.
False
Coaxial cable is frequently used as the cabling within a LAN.
False
If the impulse spike interferes with an analog signal, removing it without affecting the original signal is extremely easy.
False
It is not possible to create a Windows Server network with multiple domains.
False
Metropolitan area networks can transfer data at fast LAN speeds, but over smaller geographic regions than typically associated with a local area network.
False
NAK represents a positive acknowledgment.
False
Near-field communications involve sending signals over distances of up to 100 meters.
False
RJ45 connectors are used for fiber-optic cables.
False
The Fast Ethernet standards are based on 1000-Mbps transmission speeds, or 1 gigabit (1 billion bits) per second.
False
The software of a switch is called the backplane.
False
When a software package is installed on a multiuser system, it is not possible for multiple users to execute multiple copies of the single program.
False
____________________ are sets of rules used by communication devices to format signals transmitted.
protocols
Tracking an analog waveform and converting it to pulses that represent the wave's height above (or below) a threshold is termed ____.
pulse amplitude modulation
When a light signal inside the cable bounces off the cable wall and back into the cable, this is called ____.
reflection
A(n) ____________________ is a device that generates a new signal by creating an exact replica of the original signal.
repeater
Connecting two wide area networks requires devices such as high-speed ____
routers
One of the more common and simpler examples of lossless compression is ____________________-length encoding.
run
In IEEE 802.3 standard for CSMA/CD, frames shorter than 64 bytes are considered ____________________, or frame fragments.
runts
The Manchester encoding schemes are called ____, because the occurrence of a regular transition is similar to seconds ticking on a clock.
self-clocking
The ____________________ layer of the OSI model is responsible for establishing sessions between users.
session
A ____has one primary function: direct the data frame to only the addressed receiver.
switch
With a(n) ____ connection, the unit of transmission is a sequence of characters.
synchronous
The ____ layer of the OSI model ensures that the data packet arriving at the final destination is identical to the data packet that left the originating station.
transport
The ______________ layer of the TCP/IP protocol suite is responsible for making sure that what leaves one end of the network arrives at the other end of the network exactly the same.
transport
Many years ago, most home users connected their computer to the Internet via a dial-up telephone line and a modem, but now the more common connection is using DSL.
true
____________________ is an encoding technique that provides a unique coding value for every character in every language, no matter what the platform.
Unicode
The ____ OS most often works via a text-based interface, although GUIs are available.
Unix
The 802.11ax standard is frequently called ____.
Wi-Fi 6
The ____________________ of a signal is the height of the wave above (or below) a given reference point.
amplitude
If a receiver has just received one packet of data with bytes numbered 600 to 700, it will respond immediately with ____.
an ACK of 701
Unfortunately, noise itself occurs as a(n) ____ waveform, and this makes it challenging, if not extremely difficult, to separate noise from an analog waveform that represents data.
analog
The top layer in the OSI model is the ____________________ layer, where the application using the network resides.
application
The data rate is measured in ____.
bits per second (bps)
A(n) ____________________ occurs when two or more workstations listen to the medium at the same moment, hear nothing, and then transmit their data at the same moment.
collision
____________________ transmission is a special form of radio transmission that uses a focused ray of light in the infrared frequency range (1012 -1014 MHz).
infrared
A(n) ____ connection is a nonphysical connection between sender and receiver that allows an exchange of commands and responses.
logical
The ____ sublayer is primarily responsible for logical addressing and providing error control and flow control information.
logical link control (llc)
____ is the process of sending data over a signal by varying either its amplitude, frequency or phase.
modulation
The technique of transmitting multiple signals over a single medium is ____________________.
multiplexing
The TCP/IP ____ layer, sometimes called the Internet layer, is roughly equivalent to OSI's network layer.
network
____ software incorporates a fairly large number of network support tools.
network monitoring
The ____ encoding scheme has a voltage change at the beginning of a 1 and no voltage change at the beginning of a 0.
nonreturn to zero inverted (NRZI)
Simple parity comes in two basic forms: even parity and ____________________ parity.
odd
The three basic components of analog and digital signals are: amplitude, frequency, and ____.
phase
The ____ layer has no awareness of the meaning of the data bits being transmitted.
physical
With ____ connections, polling is not necessary because there is only one terminal per line.
point-to-point
The only USB connector type that is reversible is ____________________.
USB-C
____ is the result of small timing irregularities that become magnified during the transmission of digital signals as the signals are passed from one device to another.
Jitter
Error bursts occur ____ percent of the time.
10 to 20
Category 5e twisted pair can keep a 1 Gbps data rate up to ____ meters.
100
The ____ standard is an early and extremely popular 802.3 standard.
10Base-T
The typical range limit for Wi-Fi 2 devices is ____.
50 meters
Isolated single-bit errors occur ____ percent of the time.
50 to 60
A modem and a dial-up telephone service provides data transfer rates of approximately ____.
56,000 bits per second (56 kbps)
____ is the Bluetooth device class that has the larger range.
Class 1
For a receiver to be able to fix an error—in a process called ____—redundant information must be present so that the receiver knows which bit or bits are in error and what their original values were.
Forward error correction
____________________ uses lasers, or, in some cases, infrared transmitting devices, to transmit data between two buildings over short distances, like across the street.
Free Space Optics
The digital encoding system is ____ used on USB 3.1 communication.
NOT 8B/10B 128B/132B?
____ technology uses digital signaling in which the cable carries only one channel of digital data.
NOT Fiber optic Baseband Coaxial?
In ____________________, the primary creates a packet of data with the address of the intended terminal and transmits the packet.
NOT TCP/IP Selection?
A ____________________ or a foil shielding is used over an insulation to isolate the conducting wire in a coaxial cable.
NOT braided shielding Braided metal shield?
Once an error in the received data transmission stream is detected, the action that the receiver takes is called ____________________.
NOT forward error correction Error Control?
____ are entities that convey meaning within a computer or computer system.
NOT signals Data?
The ____ was not created by a standards-making organization but by a group of computer scientists.
TCP/IP protocol suite
____ modulation, which is commonly employed in contemporary modems, uses each signal change to represent 4 bits.
Quadrature amplitude
____is the RAID technique also called "striping."
RAID 0
According to ____________________ data is broken into pieces (stripes) and stored across three or more drives. Parity information (error-checking code) is interleaved with the striped data, not separated onto a separate drive. This configuration maximizes performance while minimizing cost and still provides reliable data recovery if a drive is lost.
RAID 5
Synchronous Optical Network (SONET) and ____________________, are powerful standards for multiplexing data streams over a single medium.
SDH
____ is probably the most common form of error control.
Sending a message back to the transmitter
____ is used to allow the numerous elements within a computer network to be managed from a single point.
Simple Network Management Protocol (SNMP)
How does the cyclic redundancy checksum work?
The CRC error-detection method treats the packet of data to be transmitted (the message) as a large polynomial. The rightmost bit of the data becomes the x0 term, the next data bit to the left is the x1 term, and so on. When a bit in the message is 1, the corresponding polynomial term is included. The transmitter takes this message polynomial and, using polynomial arithmetic, divides it by a given generating polynomial, and produces a quotient and a remainder. The quotient is discarded, but the remainder (in bit form) is appended to the end of the original message polynomial, and this combined unit is transmitted over the medium. When the data plus remainder arrive at the destination, the same generating polynomial is used to detect an error. The receiver divides the incoming data (the original message polynomial plus the remainder) by the exact same generating polynomial that was used by the transmitter. If no errors were introduced during data transmission, the division should produce a remainder of zero. If an error was introduced during transmission, the arriving original message polynomial plus the remainder will not divide evenly by the generating polynomial and will produce a nonzero remainder, signaling an error condition.
The header of the ____________________ layer has port addresses for both the sender and receiver devices.
Transport
A CDN is a distributed storage structure that allows customers to store files in locations closer to where their users are located.
True
AD is one of the components of Microsoft Windows Server.
True
ASCII is one of the supported code charts in Unicode.
True
Because white noise is relatively continuous, it can be reduced significantly but never completely eliminated.
True
Both frequency division multiplexing and synchronous time division multiplexing can waste unused transmission space.
True
Data is information that has been translated into a form that is more conducive to storage, transmission, and calculation.
True
Data transmission speed is the number of bits per second that can be transmitted.
True
Electromagnetic interference can be reduced with proper shielding, but it cannot be completely avoided unless you use fiber-optic cable.
True
Examples of real-time applications usually include streaming voice, video, and music.
True
Fiber-optic cable cannot generate nor be disrupted by electromagnetic interference.
True
IBM mainframe computers are major users of the EBCDIC character set.
True
Installing special filters for analog signals and digital signal regeneration for digital signals helps in preventing white noise.
True
Like signals, data can be analog or digital.
True
Link aggregation allows you to combine two or more data paths, or links, into one higher-speed link.
True
Linux shares many of the same advantages and disadvantages as Unix.
True
Network architectures are cohesive layers of protocols defining a set of communication services.
True
One of the most common forms of data transmitted between a transmitter and a receiver is textual data.
True
SD-branch technology is one of the possible instances of SDN.
True
The bus/tree topology was the first physical design used when local area networks became commercially available in the late 1970s.
True
With the CSMA/CD protocol, only one workstation at a time can transmit.
True
