Net125 Chapter 3 and 4

includes Header: contains control information, such as addressing, and is located at the beginning of the PDU. Data: contains the IP header, transport layer header, and application data. Trailer: contains control information for error detection added to the end of the PDU.

Data link layer frame

: can distort and corrupt data signals being carried by copper media.

Electromagnetic interference

(LC) little or local connector. Used with single-mode fiber and also supports multimode fiber.

Lucent Connector

Resolves final delivery issues and performs actual delivery to user's mailbox

MDA

Forwards mail between servers using SMTP and receives mail from client

MTA

client used to access and read mail and retrieves

MUA

Data signals are sent along with a clock signal which occurs evenly spaced time durations referred to as the bit time.

Synchronous signaling

Duration/ID - 2: Time required to transmit DA - 6: Destination Address: MAC SA - 6: Source Address: MAC RA - 6: Receiver Address, MAC address identifies wireless device that is immediate recipient of frame Sequence Control - 2: indicates seq number TA - 6: Transmitter Address, MAC address identifies wireless device that transmitted frame Frame Body - 0 - 2312: contains info being transported FCS field: 32-bit CRC

802.11 Wireless LAN Protocol Frame Control

5 GHz frequency band, max speed 54 Mb/s, not backward compatible.

802.11a

5 GHz frequency band, max speed 1.3 Gb/s, backward compatible to 802.11a/n

802.11ac

2.4 GHz, 5 GHz, and 60 GHz, max speed 7 Gb/s, backward compatible to 802.11a/b/g/n/ac

802.11ad

2.4 GHz frequency band, max speed 11 Mb/s, not backward compatible.

802.11b

2.4 GHz frequency band, max speed 54 Mb/s, backward compatible to 802.11b

802.11g

2.4 GHz and 5 GHz frequency band, max speed 600 Mb/s, backward compatible to 802.11a/b/g

802.11n

(AM) a transmission technique in which the amplitude of the carrier varies in accordance with the signal

Amplitude modulation

Data signals are transmitted without an associated clock signal. The time spacing between data characters or blocks may be of arbitrary duration, meaning the spacing is not standardized.

Asynchronous signaling

All end systems are chained to each other and terminated in some form on each end.

Bus topology

Consists of: 1. Copper conductor used to transmit electronic signals. 2. Copper conductor is surrounded by a layer of flexible plastic insulation. 3. Insulating material is surrounded in a woven copper braid, or metallic foil, that acts as the second wire in the circuit and as a shield for the inner conductor. Also reduces the amount of outside electromagnetic interference. 4. Entire cable is covered with a cable jacket to protect it from minor physical damage.

Coaxial Cable

All nodes compete for the use of the medium but have a plan if there are collisions.

Contention-based access

Network devices take turns, in sequence, to access the medium. No collisions.

Controlled Access Method

Each node has its own time to use the medium.

Controlled access

Fiber Optic Cable Consists of

Core, Cladding, Jacket

Used to interconnect similar devices together, ex. switch to a switch. One end of the cable will be different than the other end.

Crossover

a disturbance caused by the electric or magnetic fields of a signal on one wire to the signal in an adjacent wire.

Crosstalk

(CRC) Transmitting node creates a logical summary of contents of the frame. This value is placed in Frame Check Sequence (FCS) field to represent contents of the frame.

Cyclic Redundancy Check

- 8 bytes: used for synchronization, also contains delimiter to mark end of the timing information. Destination - 6 bytes: 48-bit MAC address Source - 6 bytes: 48-bit MAC address Type - 2 bytes: value to indicate which upper layer protocol will receive data after Ethernet process complete. Data - 46 - 1500 bytes: PDU, typically IPv4 packet Frame Check Sequence - 4 bytes: value used to check for damaged frames.

Ethernet Protocol Preamble

topology Central intermediate devices interconnect other star topologies.

Extended star or hybrid

(FM) a method of transmission in which the carrier frequency varies in accordance with the signal

Frequency modulation

communication Both devices can transmit and receive on the media at the same time. The data link layer assumes that the media is available for transmission for both nodes at any time. Therefore, there is no media arbitration necessary in the data link layer.

Full-duplex

the measure of usable data transferred over a given period of time. Goodput is throughput minus traffic overhead for establishing sessions, acknowledgements, and encapsulation.

Goodput

Which protocol is used to transfer web pages from server to client?

HTTP

Which protocols use authentication and encryption to secure data traveling between client and server?

HTTPS/SSH

communication Both devices can both transmit and receive on the media but cannot do so simultaneously. Ethernet has established arbitration rules for resolving conflicts arising from instances when more than one station attempts to transmit at the same time.

Half-duplex

topology a central site interconnects branch sites using point-to-point links

Hub and spoke

(LLC) Upper sublayer that defines the software processes that provide services to the network layer protocols. It places information in the frame that identifies which network layer protocol is being used for the frame. This allows multiple Layer 3 protocols, such as IPv4 and IPv6, to utilize the same network interface and media.

Logical Link Control

Two sublayers of data link layer

Logical Link Control, Media Access Control

the way a network transfers frames from one node to the next. This arrangement consists of virtual connections between the nodes of a network.

Logical topology

Lower sublayer that defines the media access processes performed by the hardware. It provides data link layer addressing and delimiting of data according to the physical signaling requirements of the medium and the type of data link layer protocol in use.

Media Access Control

requires that every end system be interconnected to every other system. all links point-to-point.

Mesh topology

(MMF) Consists of a larger core and uses LED emitters to send light pulses. Light from an LED enters the multimode fiber at different angles.

Multimode fiber

physical connections and identifies how end devices and infrastructure devices such as routers, switches, and wireless access points are interconnected.

Physical topology

Protocol used to deliver frames between two nodes. Flag - 1 byte: indicates beginning or end of frame. Address - 1 byte: contains standard PPP broadcast address Control - 1 byte: calls for transmission of user data in an unsequenced frame. Protocol - 2 bytes: identify the protocol encapsulated in the data field of the frame. Data - variable: contain the datagram for the protocol. Frame Check Sequence - 2 or 4 bytes: error detection.

Point-to-Point Protocol (PPP)

topology permanent link between 2 endpoints

Point-to-point

(PCM) a technique in which an analog signal, such as a voice, is converted into a digital signal by sampling the signal's amplitude and expressing the different amplitudes as a binary number. The sampling rate must be at least twice the highest frequency in the signal.

Pulse-coded modulation

are connected to their respective neighbor forming a ring.

Ring End systems

Cisco proprietary cable used to connect to a router or switch console port

Rollover

Which three layers of the OSI model make up the Application layer of the TCP/IP model?

Session, Presentation, Application

cable (STP) Two variations: 1. shields the entire bundle of wires with foil eliminating virtually all interference. 2. shields the entire bundle of wires as well as the individual wire pairs with foil eliminating all interference.

Shielded twisted-pair

(SMF) Consists of a very small core and uses expensive laser technology to send a single ray of light. Popular in long-distance situations spanning hundreds of kilometers.

Single-mode fiber

Wireless LAN technology, aka Wi-Fi. Uses a contention or non-deterministic system with a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) media access process.

Standard IEEE 802.11

Wireless Personal Area Network (WPAN) standard, aka "Bluetooth", uses a device pairing process to communicate over distances from 1 to 100 meters.

Standard IEEE 802.15

Worldwide Interoperability for Microwave Access (WIMAX), uses point-to-multipoint topology to provide wireless broadband access.

Standard IEEE 802.16

End devices are connected to a central intermediate device. Most common physical LAN topology.

Star topology

(ST) bayonet style connector widely used with multimode fiber

Straight-Tip

3 types of fiber optic connectors

Straight-Tip, Subscriber Connector, Lucent Connector

(SC) square connector or standard connector. used with multimode and single-mode fiber.

Subscriber Connector

layer is equivalent to what layer of OSI Data link layer and physical layer

TCP/IP network access

the measure of the transfer bits across the media over a given period of time Factors that influence throughput: Amount of traffic Type of traffic Latency created by the number of network devices encountered between source and destination

Throughput

3 main types of copper media

Unshielded Twisted-Pair (UTP), Shielded Twisted-Pair (STP), Coaxial

cable (UTP) Used for interconnecting network hosts with intermediate networking devices, such as switches and routers. Consists of four pairs of color-coded wires that have been twisted together and then encased in a flexible plastic sheath.

Unshielded twisted-pair

A network administrator is designing a network for a new branch office of twenty-five users. What are the advantages of using a client-server model? (Choose two.) a. centralized administration b. does not require specialized software c. security is easier to enforce d. lower cost implementation e. provides a single point of failure

a,c

What are two forms of application layer software? (Choose two.) a. applications b. dialogs c. requests d. services e. syntax

a,d

What are three properties of peer-to-peer applications? (Choose three.) a. acts as both a client and server within the same communication. b. requires centralized account administration. c. can be used in client-server networks. d. requires a direct physical connection between devices. e. centralized authentication is required.

a.b.c

What is the purpose of resource records in DNS? a. temporarily holds resolved entries b. used by the server to resolve names c. sent by the client to during a query d. passes authentication information between the server and client

b

18. What are two characteristics of clients in data networks? (Choose two.) a. use daemons b. initiate data exchanges c. are repositories of data d. may upload data to servers e. listen for requests from servers

b,d

What three protocols operate at the Application layer of the OSI model? (Choose three.) a. ARP b. DNS c. PPP d. SMTP e. POP f. ICMP

b,d,e

Which statements are correct concerning the role of the MTA in handling email? (Choose three.) a. routes email to the MDA on other servers b. receives email from the client's MUA c. receives email via the POP3 protocol d. passes email to the MDA for final delivery e. uses SMTP to route email between servers f. delivers email to clients via the POP3 protocol

b,d,e

A small home network has been installed to interconnect three computers together for gaming and file sharing. What two properties represent this network type? (Choose two.) a. User accounts are centralized. b. Security is difficult to enforce. c. Specialized operating system software is required. d. File permissions are controlled by a single computer. e. A computer that responds to a file sharing request is functioning as a server.

b,e

What is the automated service that matches resource names with the required IP address? a. HTTP b. SSH c. FQDN d. DNS e. Telnet f. SMTP

b,e

Which application layer protocols correctly match a corresponding function? (Choose two.) a. DNS dynamically allocates IP addresses to hosts b. HTTP transfers data from a web server to a client c. POP delivers email from the client to the server email server d. SMTP supports file sharing e. Telnet provides a virtual connection for remote access

b,e

1. What application layer protocol is commonly used to support for file transfers between a client and a server? a. HTML b. HTTP c, FTP d. Telnet

c

What application layer protocol describes the services that are used for file sharing in Microsoft networks? a. DHCP b. DNS c. SMB d. SMTP e. Telnet

c

What is the role of the OSI application layer? a. provides segmentation of data b. provides encryption and conversion of data c. provides the interface between the applications on either end of the network d. provides control of all the data flowing between the source and destination devices

c

What are two characteristics of peer-to-peer networks? (Choose two.) a. scalable b. one way data flow c. decentralized resources d. centralized user accounts e. resource sharing without a dedicated server

c,e

Which email components are used to forward mail between servers? (Choose two.) a. MDA b. IMAP c. MTA d. POP e. SMTP f. MUA

c,e

How does the application layer on a server usually process multiple client request for services? a. ceases all connections to the service b. denies multiple connections to a single daemon c. suspends the current connection to allow the new connection d. uses support from lower layer functions to distinguish between connections to the service

d

Which two protocols are used to control the transfer of web resources from a web server to a client browser? (Choose two.) a. ASP b. FTP c. HTML d. HTTP e. HTTPS f. IP

d,e

Which layer of the OSI model supplies services that allow user to interface with the network? a. physical b. session c. network d. presentation e. application f. transport

e