Multiple Choices:
1. The process-to-process delivery of the entire message is the responsibility of the ______layer.
a. Network
b. Transport
c. Application
d. Physical
2. The ______layer is the layer closest to the transmission medium.
a. Physical
b. Data link
c. Network
d. Transport
3. Mail services are available to network users through the ______layer.
a. Data link
b. Physical
c. Transport
d. Application
4. As the data packet moves from the lower to the upper layers, headers are ______
a. Added
b. Subtracted
c. Rearranged
d. Modified
5. As the data packet moves from the upper to the lower layers, headers are ______
a. Added
b. Removed
c. Rearranged
d. Modified
6. The ______layer lies between the network layer and the application layer.
a. Physical
b. Data link
c. Transport
d. None of the above
7. Layer 2 lies between the physical layer and the ______layer.
a. Network
b. Data link
c. Transport
d. None of the above
8. When data are transmitted from device A to device B, the header from A’s layer 4 is read by B’s ______layer.
a. Physical
b. Transport
c. Application
d. None of the above
9. The ______layer changes bits into electromagnetic signals.
a. Physical
b. Data link
c. Transport
d. None of the above
10. The physical layer is concerned with the transmission of ______over the physical medium.
a. Programs
b. Dialogs
c. Protocols
d. Bits
11. Which layer functions as a liaison between user support layers and network support layers?
a. Network layer
b. Physical layer
c. Transport layer
d. Application layer
12. What is the main function of the transport layer?
a. Node-to-node delivery
b. Process-to-process delivery
c. Synchronization
d. Updating and maintenance of routing tables
13. Which of the following is an application layer service?
a. Remote log-in
b. File transfer and access
c. Mail service
d. All the above
Exercises (From the text book -Data communication and networking-)
15- How are OSI and ISO related to each other?
16- If the data link layer can detect errors between hops, why do you think we need another checking mechanism at the transport layer?
17- In Figure 2.22, computer A sends a message to computer D via LANl, router Rl, and LAN2. Show the contents of the packets and frames at the network and data link layer for each hop interface.
18- Suppose a computer sends a packet at the network layer to another computer somewhere in the Internet. The logical destination address of the packet is corrupted. What happens to the packet? How can the source computer be informed of the situation?
19-Match the following to one or more layers of the OSl model:
a. Communicates directly with user's application program
b. Error correction and retransmission
c. Mechanical, electrical, and functional interface
d. Responsibility for carrying frames between adjacent nodes
20- Match the following to one or more layers of the OSI model:
a. Establishes, manages, and terminates sessions
b. Format and code conversion services
c. Ensures reliable transmission of data
d. Log-in and log-out procedures
e. Provides independence from differences in data representation
21- Suppose a computer sends a frame to another computer on a bus topology Local Area Network (LAN). The physical destination address of the frame is corrupted during the transmission. What happens to the frame? How can the sender be informed about the situation?
22- In Figure 2.22, assume that the communication is between a process running at computer A with port address i and a process running at computer D with port address j. Show the contents of packets and frames at the network, data link, and transport layer for each hop.
23- Match the following to one or more layers of the OSI model:
a. Flow control
b. Route determination
c. Provides access for the end user
d. Interface to transmission media
24- Match the following to one or more layers of the OSI model:
a. Transmission of bit stream across physical medium
b. Defines frames
c. Reliable process-to-process message delivery
d. Route selection
e. Provides user services such as e-mail and file transfer
25- Suppose a computer sends a packet at the transport layer to another computer somewhere in the Internet. There is no process with the destination port address running at the destination computer. What will happen?
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