Chapter Three

Question 1

Source

Answer 1

the originator of a message

Question 2

Destination

Answer 2

the device that is the intended recipient of the message

Question 3

Channel

Answer 3

a communication path over a medium used to transport information from a sender to a receiver. Multiple channels can be multiplexed over a single cable

Question 4

Encoding

Answer 4

a process by which bits are represented on a medium

Question 5

Decoding

Answer 5

to convert from one form to another

Question 5

Encapsulation

Answer 5

the process by which a device adds networking headers and trailers to data from an application for the eventual transmission of the data onto a transmission medium

Question 6

De-encapsulation

Answer 6

see decapsulation; a process by which an end device, after it receives data over some transmission medium, examines the headers and trailers at each successively higher layer and eventually hands the data to the correct application. Sometimes called de-encapsulation

Question 7

Flow Control

Answer 7

the management of data flow between devices in a network. It is used to prevent too much data from arriving before a device can handle it, causing data overflow

Question 8

Response Timeout

Answer 8

the amount of time a service waits on a response before taking some action. A protocol defines how long a service waits and what action is taken if a response timeout occurs.

Question 9

Access Method

Answer 9

a set of rules used by LAN hardware to direct traffic on the network. It determines which host or device uses the LAN next

Question 10

Protocol

Answer 10

a written specification that defines what tasks a service or device should perform. Each protocol defines messages, often in the form of headers, plus the rules and processes by which the messages are used to achieve some state purpose

Question 10

Unicast

Answer 10

a type of message sent to a single network destination

Question 11

Broadcast

Answer 11

a form of transmission in which one device transmits to all devices within the network or on another network

Question 12

Multicast

Answer 12

a message sent to selected hosts that are part of a group. A single packet is copied by the network and sent to a specific subset of network addresses. These addresses are specified in the destination address field

Question 13

Protocol Suite

Answer 13

a delineation of networking protocols and standards into different categories, called layers, along with definitions of which sets of standards and protocols need to be implements to create products that can be used to create a working network

Question 14

Reference Model

Answer 14

a conceptual framework to help understand and implement the relationships between various protocols

Question 15

Protocol Data Unit (PDU

Answer 15

– a generic term that refers to the data, headers, and trailers, about which a particular networking layer is concerned

Question 15

Segmentation

Answer 15

in TCP, the process of breaking a large chunk of fata into small enough pieces to fit within a TCP segment without breaking any rules about the maximum amount of data allowed in a segment

Question 16

Multiplexing

Answer 16

a process in which multiple digital data streams are combined into one signal

Question 17

Ethernet

Answer 17

a baseband LAN specification invented by Xerox Corporation and developed jointly by Xerox, Intel, and Digital Equipment Corporation. Ethernet networks use CSMA/CD and run over a variety of cable types at 10 Mbps. Ethernet is similar to the IEEE 802.3 series

Question 18

Default Gateway

Answer 18

a device on a network that serves as an access point to other networks. A default gateway is used by a host to forward IP packets that have destination addresses outside the local subnet. A router interface is typically used as the default gateway. When a computer needs to send a packet to another subset, it sends the packet to its default gateway—also known as the default router

Question 19

Which of the following are standards organizations?
a. IANA
b. TCP/IP
c. IEEE
d. IETF
e. OSI
f. MAC

Answer 19

A, C, and D. IANA, IEEE, and IETF are standards organzations. TCP/IP and OSI are protocol suites and models, and MAC is a sublayer for LANs and WLANs

Question 20

What type of communication sends a message to all devices on a local area network?
a. broadcast
b. multicast
c. unicast
d. allcast

Answer 20

A. Broadcast communication is used to send a message to all devices in a LAN, it is on-to-all communication, and multicast is for one-to-group communication. Allcast is not a type of communicaion.

Question 21

In computer communication, what is the purpose of message encoding?
a. to convert information to the appropriate form for transmission
b. to interpret information
c. to break large messages into smaller frames
d. to negotiate correct timing for successful communications

Answer 21

A. encoding is the process of converting information into another acceptable form for transmission.

Question 22

Which message delivery option is used when all devices need to receive the same message simultaneously? a. duplex b. unicast c. multicast d. broadcast

Answer 22

D. Broadcast communication is used to send a message to all devices in a LAN; it is one-to-all communications. Unicast is one-to-one communication, and multicast is one-to-group communication.

Question 23

What are two benefits of using a layered-network model? (choose two) a. it assists in protocol design b. it speeds up packet delivery c. it prevents designers from creating their own model d. it prevents technology in one layer from affecting other layers e. it ensures that adevice at one layer can function at the next higher layer

Answer 23

A and D. One benefit of a layered model is assisting in protocol design because protocols that operate at a specific layer have defined information that they act upon and a defined interface to the layers above and below. Another benefit is preventing technology or capability changes in one layer from affecting other layers above and below.

Question 24

What is the protocols in data communications? a. specifying the bandwidth of the channel or medium for each type of communication b. specifying the device operating systems that will support the communication c. providing the rules required for a specific type of communication to occur d. dictating the content of a message sent during communication

Answer 24

C. protocols are the rules that govern communications

Question 25

Which logical address is used for delivery of data to a remote network? a. desination of MAC address b. desination of IP address c. destination port number d. source MAC address e. source IP address

Answer 25

B. IP addressing is used to deliver data to a device on the same network and to devices on other networks. The destination IP address is the ultimate destination of the message

Question 26

What is the general term that is used to describe a piece of data at any layer of a networking model? a. frame b. packet c. protocol data unit d. segment

Answer 26

C. the term protocol data unit (PDU) is used to describe data at different layers of a networking model. For example, a frame is the PDU used at Layer 2 of the OSI model

Question 27

What two protocols function at the internet layer? (choose two) a. POP b. BOOTP c. ICMP d. IP e. Ethernet

Answer 27

C and D. ICMP and IP are protocols at the internet layer of the TCP?IP model. POP and BOOTP are application layer protocols, and Ethernet is an access layer protocol.

Question 28

Which layer of the OSI model defines services to segment and reassemble data for individual communications between end devices? a. application b. presentation c. session d. transport e. network

Answer 28

D. the transport layer is responsible for segmenting data when transmitted and reassembling data when it is received

Question 29

Which type of communication sends a message to a group of host destinations simultaneously? a. broadcast b. multicast c. unicast d. anycast

Answer 29

B. multicast is one-to-group communication, Broadcast is one-to-all communication, and unicast is one-to-one communication.

Question 30

What process is used to receive transmitted data and convert it into a readable message? a. access control b. decoding c. encapsulation d. flow control

Answer 30

B. encoding is the process of converting information into another acceptable form for transmission. Decoding reverses this process to interpret the information.

Question 31

What is done to an IP packet before it is transmitted over the physical medium? a. it is tagged with information, guaranteeing reliable delivery b. it is segmented into smaller individual pieces c. it is encapsulated into a TCP segment d. it is encapsulated in a Layer 2 frame

Answer 31

D. an IP packet is encapsulated in an Layer 2 frame to be transmitted over the physical medium. Layer 2 is for NIC-to-NIC, communication on the same network

Question 32

What process is used to place one message inside another message for transfer from a source to a destination? a. access control b. decoding c. encapsulation d. flow control

Answer 32

C. encapsulation is the process of prepending the proper protocol header a the next, lower layer

Question 33

A web client is sending a request for a web page to a web server. From the perspective of the client, what is the correct order of the protocol stack that is used to prepare the request for transmission? a. HTTP, IP, TCP, Ethernet b. HTTP, TCP, IP, Ethernet c. Ethernet, TCP, IP, and HTTP d. Ethernet, IP, TCP, HTTP

Answer 33

B. to request a web page from a server, the web client prepares the HTTP request, then encapsulates it in a TCP header, then encapsulates it in an IP header, and finally encapsulates it in an Ethernet header and trailer