Cisco CCNA考试题库大全

[CCNA考试题库]Cisco CCNA考试题库大全

1.What is the correct order for

    the OSI model? 

　　P=Presentation, S=Session, D=Datalink,

　　Ph=Physical, T=Transport, A= Application,

　　N=Network 

　　A. P S A PH D N T 
　　B. A P S T N D PH 
　　C. PH D N T A S P 
　　D. P S A T N D PH 

It is crucial you not only memorize this

and know what each layer does. 

　　2. What is encapsulation? 

　　A. Putting the header on an incoming frame 
　　B. Putting a header on an incoming segment 
　　C. Putting a header on an outgoing frame 
　　D. Putting a header on an outgoing bit 

　　This also includes trailers and can be put on segments,

　packets, and frames. 

　　3. Which layer is most concerned with user applications? 

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

　　4. Which of the following is de-encapsulation? 

　　A. Stripping the header from a frame 
　　B. Putting a header on a segment 
　　C. Putting a header on a frame 
　　D. Stripping a frame from a link 
　　

 This also includes trailers as in question 2. 

　　5. What layer converts data into segments? 

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

　　 
　
　　6. What layer converts data into Packets? 

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

　

　　7. What layer converts data into Frames? 

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

　　8. What layer converts data into bits? 

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

　　

　　All of the layers need to convert data into something that

　　they can pass down to the next level, with the exception of

　　the Application layer which hands data to the Presentation layer.

　　The Presentation layer encrypts, and compresses

　　before sending it to

　　the Session layer for it s first conversion. 

　　9. Which layer is most concerned with getting data

　　from the beginning to the final destination? 
　　A. Application 
　　B. Presentation 
　　C. Session 
　　D. Transport 

 

　　The transport layer is most concerned with reliable transportation

　　from one end to the other. 

　　10. Which of the following is not a part

　　of the Session layer? 

　　A. Establishing a session 
　　B. Ensuring error free segments 
　　C. Ending a session

　　D. Keeping the sender and receiver from sending a message

　　at the same time  That is the job of the Transport layer. 

　　11. Which of the following is not a job

　for the presentation layer? Choose 2 

　　A. Data representation 
　　B. Compression 
　　C. Dialog management 
　　D. Transmission 
　　E. Encryption 

 

　　C is handled by the session layer, and D is handled

　　by the Transport layer 

　　12. What does Peer to Peer communication involve? 

　　A. Each layer communication with the layer below it

        B. Each layer communication with layer above it 
　    C. Each layer communicating with adjacent layer in another system 
　　D. Each layer communication with it s corresponding layer in 

　　another system 

　　Answer D.

　　Answer C sounds correct also, but adjacent

　　and corresponding are two different things.

　　The session layer can only communicate with the session

　　layer in another system for example. 

　　13. Why does the industry use a layered model?

　　Choose all correct 

　　A. When you enhance one layer it doesn t affect the other layers 
　　B. Design and development can be made in a modular fashion 
　　C. Network operations can be simplified 
　　D. Troubleshooting can be simplified. 

　
      14. Which two of the following are not

       from the physical layer? 

　　A. SDLC 
　　B. V.35 
　　C. HSSI 
　　D. ISDN 
　　E. RS-232 

　　Answer A D.

SDLC and ISDN are WAN protocols that function at the data link layer 

　　15. Which two answers are functions of the OSI model"s

 network layer? 

　　A. Sequencing of frames 
　　B. Path determination 
　　C. Packet switching 
　　D. Packet sequencing 

　　Answer B C.

Sequencing is done at the data link layer. D is fictional. 

　16. What is an example of a MAC address? 

　　A. Az32:6362:2434 
　　B. Sj:2817:8288 
　　C. GGG:354:665 
　　D. A625:cbdf:6525 

 

 　　The address is a 48 bit address which

　　requires 12 Hex digits.A hex digit can t be past

　　the letter F. Hex stands for 16. 1-9 and A-F

　　make up numbers that are valid. 

　　17. Which of the following is not part of

　　the data link layer? 

　　A. Transports data across the physical link 
　　B. Performs physical addressing 
　　C. Performs flow control 
　　D. Determines network topology 
　　E. Terminates a session 
　　This is part of the session layer 

　　18. Which of the following are data link protocols? 

　　A. HDLC 
　　B. FTP 
　　C. SQL 
　　D. ISDN 
　　E. Token Ring 

 

　　FTP is an application and SQL is a session layer protocol. 

　　19. Of the following address AA77:3827:EF54,

    which of the following is the vendor portion? 

　　A. AA7738 
　　B. 27EF54 
　　C. AA77 
　　D. EF54 
　　The vendor code is how you can tell who made the card.

　　The last 6 digits are the physical address.

20. Which of the following are examples of layer 3 addressing? 

A. 165.33.4.34 
B. AA77:3827:EF54 
C. HHHH:hg:7654 
D. 76 

 The first is a TCPIP address and the second is an IPX address 

21. What is considered Layer 3 addressing? 

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

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 

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 

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 

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 

 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. FDDI 
E. ISDN 

Ethernet and FDDI are LAN protocols. 

27. Which of the following will allow you to view NVRAM s contents? 

A. show configuration 
B. show protocols 
C. show version 
D. show running-config 
E. show startup-config 

Answer A E. These show the backup configuration stored in NVRAM.

The other anwsers allow youto view RAM. 

28. Which of the following contains the OS image? 

A. Flash 
B. NVRAM 
C. RAM 
D. Interfaces 

ROM will be used if Flash is unavailable. NVRAM is the backup

configuration, and RAM is the active configuration 

29. Which of the following indicates the router is in privilege mode? 

A. Router# 
B. Router> 
C. Router- 
D. Router* 

 Answer B shows the router in user mode. 

30. What does "show cdp neighbors" not show? Neighbors_________ 

A. device id 
B. hardware platform 
C. ios version 
D. port type and number 
31. Which of the following will

show you the clock? 

A. cl? 
B. Cl ? 
C. Clock? 
D. Clock ? 

 By typing this the router will finish the command

and show the clock. 

32. CDP operates at which layer? 

A. Transport 
B. Network 
C. Data link 
D. Physical 

 CDP allows a network device to exchange frames with

other directly connected networked devices. 

33. Which command does not show two devices are not routing packets

between them successfully? 

A. ping  
B. show interface 
C. trace 
D. telnet 

Answer A C D. With these commands you can tell

whether or not you have communication.

Show interface just verifies there is a connection 

34. What keystrokes shows the possible commands in privilege mode? 

A. help 
B. h 
C. ctrl+h 
D. ? 

Answers A and B will give a brief description

when typed, and C is not valid. 

35. Which two items contain versions of the router s configuration file? 

A. flash 
B. nvram 
C. ram 
D. rom 

A and D contain the OS. 

36. Which of the following commands will allow you

to review the contents of RAM? 
A. show configuration 
B. show protocols 
C. show version 
D. show running-config 
E. show startup-config 

 A and E allow you to see NVRAM. 

37. Which of the following will allow you to add, modify,

or delete commands in the startup configuration file? 

A. show startup-config 
B. show running-config 
C. configure terminal 
D. configure memory 

Answer C allows you to change items in the running configuration file 

38. Which command would be used to restore a configuration file to RAM? 
________TFTP running-config 

A. router#copy 
B. router>copy 
C. router*copy 
D. router^copy 

You must be in privilege mode when executing this, which is why you see the # sign. 

39. Which of the following commands will display the running configuration

file to a terminal? 

A. show running-config 
B. show router-config 
C. router#show flash 
D. router>show version 

It can only be shown in privilege mode. 

40. If you need to copy the currently executing configuration file into NVRAM,

which command would you use? 

A. router#copy startup-config running-config 
B. router#copy startup-config TFTP 
C. router#copy running-config startup-config 
D. router>copy startup-config running-config 

 Answers ABC show that the router is in privilege mode

which is necessary to complete this action, but only C shows the correct syntax.

 

41 Which of the following commands would not set a password on a Cisco router? 

A. router(config)#enable secret 
B. router(config-line)#password test 
C. router(config)#service encryption password 
D. router(config)#enable password 

This command is used to encrypt passwords in configuration files. 

42. Which of the following would cause a router to boot into

the initial configuration dialog after powering has cycled? 

A. Someone had copied the startup configuration file in a TFTP server 
B. The running configuration file was copied to the startup configuration file 
C. It is the first time router has ever been turned on 
D. The write erase command was executed immediately before powering down the router. 

 These two scenarios describe what will happen when the router needs to

use NVRAM to boot if it cannot find the configuration file.

43. What would cause a router to boot from ROM? 

A. 0x3202 
B. 0x2302 
C. 0x2101 
D. 0x2103 

A configuration register of 1 or 0 will cause the router to boot from ROM. 

44. Where does the running config file exist? 

A. NVRAM 
B. ROM 
C. RAM 
D. Flash 

This file is erased if the router is reloaded or rebooted. 

45. How do you back up a router? 

A. router#copy running-config startup-configuration 
B. router(config)#copy TFTP flash 
C. router#copy flash TFTP 
D. router#copy flash NVRAM 

You can copy the file to a TFTP server or other storage device.

46. Which of the following is not valid? 

A. router>show version 
B. router#show running-config 
C. router#show startup-config 
D. router#show RAM 

Answer D. 

47. Which of the following are basic 

router functions? 

A. Packet switching 
B. Packet filtering 
C. Path determination 
D. Rapid convergence  

 Packets get switched once they are determined by the router where to go. 

48. Which of the following is not an interior routing protocol? 

A. RIP 
B. IGRP 
C. OSPF 
D. BGP 

BGP is an exterior routing protocol designed to communicate

between autonomous systems. 

49. Which of the following routing protocols communicate r

outer information by sending the state of it s links to all routers

in it s domain? 

A. BGP 
B. RIP 
C. IGRP 
D. OSPF 

This is a "link state" routing protocol. RIP and IGRP are distance vector,

and BGP communicates reachability between domains. 

50. What is a problem caused by distance vector routing protocols? 

A. Split horizon 
B. Route Poison 
C. Counting to infinity 
D. Max hop count 
E. Hold down timers 

Answers ABDE are counter measures to the counting to infinity problem caused

by distance vector protocols. 

51. What router command will display the routing protocol settings configured

on a router? 

A. show protocol 
B. Show routing protocol 
C.Show ip protocol 
D. Show running-config 

This also displays timers, neighbors, and next update info. 

52. What helps mitigate the problems with link state protocols? Choose 2 

A. Minimize router resource usage. 
B. Coordinate updates 
C. Minimum hop counts 
D. Distance vectoring 

53. Which router commands will enable RIP for 176.18.0.0? Choose 2 

A. router rip 
B. network 176.18.0.0 
C. network rip 
D. network rip 176.18.0.0 

Router rip enables rip. Answer B enable the router to advertise to other routers

that it is available. You must be in the global configuration prompt. 

54. Which of the following is a disadvantage with the link state protocol?

Choose 3 
A. hold down counters 
B. unsynchronized updates 
C. high network bandwidth usage 
D. high router resource usage 

As link state packets flood the network, high network bandwidth can be a problem. 

55. Which of the following exist at the application layer of the TCPIP model?

Choose 3 

A. SMTP 
B. FTP 
C. ICMP 
D. RIP 
E. IGRP 

Answers D and E and routing protocols. 

56. Which of the following translate Fully Qualified Domain Names

into IP addresses? 

A. Wins 
B. DNS 
C. SNMP 
D. TCP 

57. Which of the following translate netbios names? 

A. Wins 
B. DNS 
C. SNMP 
D. TCP 

Netbios names are the names of the computers specified in the identification tab

in the network neighborhood properties. 

58. Which of the following is not done by TCP? 

A. Subnetting 
B. Error checking 
C. Sequencing 
D. Flow control 

59. What does UDP and TCP have in common? Choose 2 

A. flow control 
B. error checking 
C. checksum 
D. provide destination and source port numbers 

UDP doesn t check for errors. 

60. Which of the following does the network layer do? Choose 2 

A. Packet switching 
B. Translating 
C. Path determination 
D. Convert signals to bits 

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. 

76. How do switches use store and forward?  

A. The switch waits only for the header to be received 

before it checks the destination address and starts

forwarding the packets  
B. 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  
C. By using a class II repeater in a collision domain  
D. By using broadcast addresses as source addresses  

Packet-switching technique in which frames are completely processed

before being forwarded out the appropriate port.

This processing includes calculating the CRC and checking the destination address.

In addition, frames must be temporarily stored until network resources

(such as an unused link) are available to forward the message. Contrast

with cut-through packet switching. 

77. Choose all of the following that are needed to support full-duplex Ethernet. 

A. Multiple paths between multiple stations on a link 
B. Full-duplex NIC cards  
C. Loop back and collision detection disabled  
D. Automatic detection of full-duplex operation by all connected stations  

Capability for simultaneous data transmission between a sending station

and a receiving station. 

78. What two types of technology does 100BaseT use? 

A. Switching with 53-byte cells  
B. CSMA/CD 
C. IEEE 802.5  
D. 802.3u  

100-Mbps baseband Fast Ethernet specification using UTP wiring.

Like the 10BaseT technology on which it is based, 100BaseT sends link

pulses over the network segment when no traffic is present. However,

these link pulses contain more information than those used in 10BaseT.

Based on the IEEE 802.3 standard.  

79. Choose all of the following that are advantages

to segmenting with routers.  

A. Manageability  
B. Flow control 
C. Explicit packet lifetime control  
D. Multiple active paths  

All of the above is correct.

A router is a Network layer device that uses one or more metrics

to determine the optimal path along which network traffic should be forwarded.

Routers forward packets from one network to another based on network layer information