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CCNA And CCENT Practice Exam Questions

10 Questions On The OSI And TCP/IP Models

By Chris Bryant, CCIE #12933

To help you on your way to the CCENT and CCNA certifications, here are 10 free questions on network models. Answers have been posted at the bottom of the page. No peeking!

1. At what layer(s) of the OSI model do authentication and encryption run?

2. Identify the OSI model layer at which each of the following devices run.

A. Router

B. Switch

C. Firewall

D. Crossover Cable

E. Rollover Cable

3. Which layer of the OSI model concerns itself with proper data formatting?

4. Which of the following protocols does NOT run at the uppermost layer of the OSI model?

A. SMTP

B. Telnet

C. FTP

D. UDP

E. SNMP

5. Which of the following does NOT describe the Transport layer of the OSI model?

A. TCP and UDP run here.

B. Data is sent in segments, not packets.

C. Data is sent in packets, not segments.

D. Offers connection-oriented and connectionless data transport services.

E. Routing takes place at this layer.

F. The Sequenced Packet Exchange protocol runs here.

6. Give two other common names for a Layer 2 address.

7. What is the basic purpose of the FCS, and at which OSI layer will we find it?

8. Which layers of the OSI model map to the TCP/IP model's Application layer?

9. Which of the following describe TCP?

A. Connection-oriented

B. Connectionless

C. Best-effort delivery

D. Allows for error detection

E. Allows "windowing"

10. Which of the following describes UDP?

A. Connectionless

B. Connection-oriented

C. Runs at the Network layer of the OSI model

D. Runs at the Transport layer of the TCP/IP model

E. Best-effort delivery

F. Delivers packets

G. Delivers segments

H. Delivers frames

Answers right after this brief and important message!

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Let's take a look at the answers!

1. Authentication runs at L7, the Application layer. Encryption runs at L6, the Presentation layer.

2. Firewalls run at the Application layer, routers run at the Network layer, switches run at the Data Link layer, and both cable types run at the Physical layer.

3. Proper data formatting is the job of the Presentation layer.

4. (D). UDP runs at the Transport layer.

5. (C, E) Data is not contained in packets at the Transport layer - we're dealing with segments at the Transport layer. Routing takes place at the Network layer. The other four statements are true.

6. L2 addresses are also known as physical addresses, MAC addresses, hardware addresses, and burned-in addresses (BIAs).

7. The data link layer can use a Frame Check Sequence (FCS) to detect errors.

8. The OSI model's Application, Presentation, and Session layers map to the TCP/IP's model's Application layer.

9. (A, D, E). TCP is connection-oriented, has error detection capabilities, and has windowing capabilities. The other two phrases, "connectionless" and "best-effort delivery", describe UDP.

10. (A, D, E, G). UDP is connectionless, runs at the Transport layer of the TCP/IP model as well as the OSI model's Transport layer, uses best-effort delivery, and delivers segments.