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

　　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.