Question

Answer the following multiple-choice questions:

1. A TCP receiver received an expected segment, without error, but yet has not ACKed the sender. What might be the reason for that?

1. It is actually a lost segment.
2. It is actually a duplicate segment.
3. The use of Stop-and-wait mechanism.
4. The use of Delayed ACK.
5. The use of a large window size.

2. If a TCP receiver received 2 segments with sequence number 34 and 58, the second segment was corrupted and discarded. What action could be taken to fix this? (Recall in TCP, ACK number is the next expected 1st byte number in the next segment & TCP uses cumulative ACK means all segments received with sequence number less than ACK number have been received correctly)

1. Receiver sends ACK number 34
2. Receiver sends ACK number 58
3. Receiver sends ACKs number 34 & 58
4. Receiver just waits for timeout

3. Receiver Window value in TCP header is used for ___________

1. Go-back N window
2. Flow control
3. Congestion avoidance
4. Establish connection

4. Comparing TCP to UDP: choose ALL CORRECT statements

1. UDP server can support multiple clients using one socket.
2. TCP server can support multiple clients using one socket.
3. TCP server can support multiple clients using multiple sockets.
4. TCP server cannot allow a client to have more than one connection socket.
5. TCP server allow a client to have more than one connection socket

5. What is NOT true about TCP congestion control?

1. TCP sender’s experience slow rate at the beginning of the connection
2. After a slow start, TCP sender’s initial rate increases slowly
3. After a slow start, TCP sender’s initial rate increases exponentially (fast)
4. when loss occurs, congestion window is cut down to half

6. A reliable data transfer mechanism in which receiver individually acknowledges all correctly received packets and sender only resends packets for which ACK not received is called:

1. Go-back-N
2. Selective repeat
3. Negative acknowledgement
4. NAK-free protocol

7. Consider a TCP connection between Host A and B. Suppose that the TCP segments traveling from Host A to Host B have source port number x and destination port number y. What are the source and destination port numbers for the segments traveling from Host B to Host A?

1. source port number x and destination port number x
2. source port number x and destination port number y
3. source port number y and destination port number x
4. source port number y and destination port number y
5. No enough information

8. Consider an RDT protocol. To find whether a received packet (at the receiver) contains new data or it is a duplicate, we can use ________________.

1. Sequence numbers
2. Acknowledgement
3. Duplicate Acknowledgement
4. Timers
5. Pipelining
6. Checksum

Answer 1

ANSWER for question (1) is option (d)- The use of Delayed ACK.

Reason: TCP delayed acknowledgment is a technique used by some transmission control protocol implementations to improve network performance.

ANSWER for question (2) is option(d)- Receiver just waits for the timeout.

Reason: Segments are discarded due to network congestion. In such cases, retranmission occurs after timeout.

ANSWER for question (3) is option(b)- Flow control protocol.

Reason: TCP uses an end-to-end flow control protocol to avoid the sender sending data too quickly for the TCP receiver to receive and process reliably.

ANSWERS for question(4) are Options (a), (b), (c), (e).

Reason: TCP allows client to have multiple sockets. Hence, option(d) is incorrect.

ANSWER for question(5) is option (c)- After a slow start, TCP sender’s initial rate increases exponentially fast.

Reason: The initial rate is low, the rate of increase is very rapid; for every acknowledged data packet.

ANSWER for question (6) is option (d)- NAK free protocol.

Reason: NAK free protocol comes RECEIVER FEEDBACK technique.

ANSWER for question (7) is option (c)- Source port number y and destination port number x. (Reason is pretty understood.)

ANSWER for question (8) is option (a)- Sequence Numbers.

Reason: This is the duty of receiver to specify sequence Number of confirmed packets.

If you are satisfied by my answer please give a thumbs up. Thank you.