Question 1.
Which of the following are reasons to have a structured data communications model?

a) It facilitates standardization.
b) It simplifies the work of developers.
c) It allows developers to make changes at one layer that automatically impact several other layers.
d) It facilitates troubleshooting.

Answer

Question 2.
Which of the following protocols are connectionless?

a) TCP
b) UDP
c) IPX
d) SPX

Answer

Question 3.
To enable hop-by-hop communications across an internetwork, you would need to install a device operating at which layer?

a) Transport
b) Physical
c) Network
d) Data Link

Answer

Answers

Question 1.
Which of the following are reasons to have a structured data communications model?

a) It facilitates standardization.
b) It simplifies the work of developers.
c) It allows developers to make changes at one layer that automatically impact several other layers.
d) It facilitates troubleshooting.

Answer
a) It facilitates standardization.
b) It simplifies the work of developers.
d) It facilitates troubleshooting.

Explanation
The OSI model, which divides communications into seven distinct "layers," is valuable for a number of reasons. One of the most important of these reasons is that it encourages standardization by separating communications into defined functions happening at each layer. Although data is passed between layers, and each layer passes services to the layer above it and receives services from the layer below it, the layers nonetheless operate relatively independently. This allows developers to alter operations at one layer without having an effect on how other layers work. It also facilitates troubleshooting by subdividing communications and allowing problem analysis to be done at each layer separately.
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CCIE Topic(s):
CCIE Objective(s):
CCNA Topic(s): a
CCNA Objective(s): a4

Question 2.
Which of the following protocols are connectionless?

a) TCP
b) UDP
c) IPX
d) SPX

Answer
b) UDP
c) IPX

Explanation
TCP and SPX are both connection-oriented protocols that perform similar functions. TCP is used for IP stacks while SPX is used for Novell NetWare IPX stacks. They both rely on an established connection between sending and receiving devices and must establish this connection before data transfer can begin. UDP and IPX, however, do not require that a connection be established between devices before communication can occur. They are often described as functioning like a postal service that sends mail but does not (usually) provide a confirmation that the letter has arrived.
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CCIE Topic(s):
CCIE Objective(s):
CCNA Topic(s): a
CCNA Objective(s): a2

Question 3.
To enable hop-by-hop communications across an internetwork, you would need to install a device operating at which layer?

a) Transport
b) Physical
c) Network
d) Data Link

Answer
a) Transport

Explanation
Devices working at the Transport layer of the OSI model are responsible for end-to-end communications across an internetwork. Such devices are most commonly clients or servers. They use network addresses of the endpoints, coupled with identifiers called port or socket numbers. Think of a port number as having the relationship to a network address that an extension number does to a telephone number. The telephone number is unique in the telephone system, but extension numbers are unique only with respect to a telephone number.
[3117]

CCIE Topic(s):
CCIE Objective(s):
CCNA Topic(s): a
CCNA Objective(s): a1