CiscoCCNA考试七十九题
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
answer b. 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
answer c. 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
answer a.
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
answer a. this also includes trailers as in question 2.
5. what layer converts data into segments?
a. application
b. presentation
c. transport
d. physical
answer c.
6. what layer converts data into packets?
a. network
b. application
c. physical
d. data link
answer a.
7. what layer converts data into frames?
a. application
b. physical
c. data link
d. transport
answer c.
8. what layer converts data into bits?
a. application
b. session
c. data link
d. physical
answer d. 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
answer d. 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
answer b. 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
answer c d. 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.
answer a b c d.
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
answer d. 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
answer e. 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
answer a d e. 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
answer a. the vendor code is how you can tell who made the card. the last 6 digits are the physical address.