思科认证考试CCNA考试七十九题(3)[1]

【网络综合 - Cisco认证试题】
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21. What is considered Layer 3 addressing?

A. Data Link Layer B. Network Layer
C. Application Layer D. None of these

Answer B. Physical is Layer 1, then data link, and then Network. This is the same
layer that routers are on.

22. What layer are Bridges on?

A. Data Link B. Physical C. Application D. Transport

Answer A. Bridges segment networks but are not able to determine addresses like the
network layer does.

23. Repeaters are on what layer?

A. Transport B. Session C. Physical D. Application

Answer C. All repeaters can do is boost a signal. An active hub is a good example
of a repeater. A switching hub is a good example of layer 3 addressing, since
switches go by network addresses and IPX addresses rather than just boost signals.
Bridges can only read mac addresses, and not the full IPX or TCPIP addresses.

24. Which of the following are considered routing protocols?

A. OSPF B. IP C. IPX D. EIGRP E. Token Ring

Answer A D. Answers B and C are routed protocols, whereas A and D are the protocols
that do the routing. This is easily confused. You can remember it by thinking that
the routing protocols that haul the routed protocols are like a tug ship pulling a
barge. The barge is full of data.

25. Which two of the following are considered connection oriented communication?

A. Setup and maintenance procedures are performed to ensure message delievery
B. A physical circuit exists between two communicating devices
C. It is a best effort type of communication
D. A virtual connection exists between the two

Answer A D. B is not a necessity, and C is not accurate. TCP is connection oriented
and UDP is not.

26. Which of the following are not WAN protocols? Choose 2

A. Frame Relay B. ATM C. Ethernet D. FDDIE. ISDN

Answer C D. Ethernet and FDDICisco认证