Cisco CCNA考试七十九题

来源：作者：出处：巧巧读书 2006-07-25 进入讨论组

61. Which of the following about ARP is true?

Choose 2

A. It is in the application layer
B. It is in the network layer
C. It maps mac addresses to ip addresses
D. It maps ip addresses to mac addresses

At the same layer are RARP, ICMP, and IP.

RARP does what is in answer C.

62. What protocol in the transport layer does

not guarantee packet delivery?

A. TCP
B. IP
C. IPX
D. UDP

It does a best effort delivery, but is faster than TCP.

63. Which of the following is a class A ip address?

A. 10.14.16.12
B. 127.0.0.1
C. 172.15.42.34
D. 209.123.32.212

64. Which of the following is a class B address?

A. 10.14.16.12
B. 127.0.0.1
C. 172.15.42.34
D. 209.123.32.212

65. Which of the following is a loop back address?

A. 10.14.16.12
B. 127.0.0.1
C. 172.15.42.34
D. 209.123.32.212

This is used to test to see if IP is configured and working properly on your pc,

66. Which of the following is a non routable ip address? Choose 2

A. 10.10.0.0
B. 192.168.0.1
C. 10.14.12.12
D. 209.32.242

Answer A B. These are good ip addresses to use behind a fire wall because

they will never be addresses that will be used on the internet.

67. Which of the following binary numbers represent 10.12.16.6

A. 00001010.00001100.00010000.00000110
B. 00011110.01010000.11001100.00110101
C. 01101010.11001010.01000101.01010011
D. 10001001.11010101.11111111.00000000

D cannot be used at all because you can t have all 1 s or 0 s

68. What does the process of AND in do?

A. It determines the value of an ip address
B. It determines the port that TCP will use
C. It determines if two ip addresses are on the same network
D. It decides the ip address subnet

You do this by writing out all the ip addresses in binary and match them

against their subnets.After you match up the 1 s and 0 s you can decide

if they are on the same network by seeing if all the numbers match.

Check the test info page for an example.

69. Which of the following is a class C address?

A. 124.12.13.44
B. 210.24.56.76
C. 127.0.0.1
D. 10.14.12.16

An address above 191 for the first octet shows a class C address.

70. Of the following address address 11100000.11000000.11110000.10000000,

what is true? Choose 2

A. It is a class C address
B. It has a host id of 192.224.128
C. It has a host id 128
D. It is a class B address.

71. Which layer is responsible for providing mechanisms for

multiplexing upper-layer application, session establishment,

and tear-down of virtual circuits?

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

72. Which layer is responsible for coordinating communication

between systems?

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

73. Which layer is responsible for negotiating data transfer syntax?

A. application
B. presentation
C. session
D. transport

74. Which of the following is a characteristic of a switch,

but not of a repeater?

A. Switches forward packets based on the IPX or IP address in the frame.
B. Switches forward packets based only on the IP address in the packet.
C. Switches forward packets based on the IP address in the frame
D. Switches forward packets based on the MAC address in the frame

Switches are network device that filters, forwards, and floods frames based

on the destination address of each frame.

The switch operates at the data link layer of the OSI model.

Switches use layer 2 addresses to filter the network

75. How does the cut-through switching technique work?

A. The LAN switch copies the entire frame into its buffers and then looks up

the destination address in its forwarding, table and determines the outgoing interface
B. The switch waits only for the header to be received

before it checks the destination address and starts forwarding the packets
C. By using broadcast addresses as source addresses
D. By using a Class II repeater in a collision domain

Packet switching approach that streams data through a switch

so that the leading edge of a packet exits the switch at the output port before

the packet finishes entering the input port. A device using cut-through packet switching reads, processes, and forwards packets

as soon as the destination address is looked up, and the outgoing port determined.

Also known as on-the-fly packet switching.

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