Explore topic-wise MCQs in Computer Networks.

This section includes 8 Mcqs, each offering curated multiple-choice questions to sharpen your Computer Networks knowledge and support exam preparation. Choose a topic below to get started.

1.

Consider two hosts P and Q connected through a router R. The maximum transfer unit (MTU) value of the link between P and R is 1500 bytes, and between R and Q is 820 bytes.A TCP segment of size 1400 bytes was transferred from P to Q through R, with IP identification value as 0 × 1234. Assume that the IP header size is 20 bytes. Further, the packet is allowed to be fragmented i. e, Don't Fragment (DF) flag in the IP header is not set by P.Which of the following statements is/are correct?

A. TCP destination port can be determined by analysing only the second fragement.
B. If the second fragment is lost, P is required to resend the whole TCP segment.
C. Two fragments are created at R and the IP datagram size carrying the second fragment is 620 bytes.
D. If the second fragment is lost, R will resend the fragment with the IP identification value 0 × 1234.
Answer» C. Two fragments are created at R and the IP datagram size carrying the second fragment is 620 bytes.
Discussion
2.

Checksum field in TCP header is

A. one's complement of sum of header and data in bytes
B. one's complement of sum of header, data and pseudo header in 16 bit words
C. dropped from IPv6 header format
D. better than md5 or sh1 methods
Answer» D. better than md5 or sh1 methods
Discussion
3.

Consider a TCP client and TCP server running on two different machines. After completing data transfer, the TCP client calls close to terminate the connection and a FIN segment is sent to the TCP server. Server-side TCP responds by sending an ACK, which is received by the client-side TCP. As per the TCP connection state diagram (RFC 793), in which state does the client-side TCP connection wait for the FIN from the server-side TCP?

A. LAST - ACK
B. TIME-WAIT
C. FIN-WAIT-1
D. FIN-WAIT-2
Answer» E.
Discussion
4.

Consider the three-way handshake mechanism followed during TCP connection establishment between hosts P and Q. Let X and Y be two random 32-bit starting sequence numbers chosen by P and Q respectively. Suppose P sends a TCP connection request message to Q with a TCP segment having SYN bit = 1, SEQ number = X, and ACK bit = 0. Suppose Q accepts the connection request. Which one of the following choices represents the information present in the TCP segment header that is sent by Q to P?

A. SYN bit = 0, SEQ number = X + 1, ACK bit = 0, ACK number = Y, FIN bit = 1
B. SYN bit = 1, SEQ number = X + 1, ACK bit = 0, ACK number = Y, FIN bit = 0
C. SYN bit = 1, SEQ number = Y, ACK bit = 1, ACK number = X, FIN bit = 0
D. SYN bit = 1, SEQ number = Y, ACK bit = 1, ACK number = X + 1, FIN bit = 0
Answer» E.
Discussion
5.

Consider the following statements.I. TCP connections are full duplexII. TCP has no option for selective acknowledgmentIII. TCP connections are message streams

A. Only I is correct
B. Only I and III are correct
C. Only II and III are correct
D. All of I, II and III are correct
Answer» B. Only I and III are correct
Discussion
6.

An ACK number of 1000 in TCP always a means that

A. 999 bytes have been successfully received
B. 1000 bytes have been successfully recieved
C. 1001 bytes have been successfully received
D. None of the above
Answer» E.
Discussion
7.

A TCP server application is programmed to listen on port number P on host S. A TCP client connected to the TCP server over the network.Consider that while the TCP connection was active, the server machine S crashed are rebooted. Assume that the client does not use the TCP keepalive timer.Which of the following behaviours is/are possible?

A. If the client sends a packet after the server reboot, it will receive a RST segment.
B. If the client was waiting to receive a packet, it may wait indefinitely.
C. It the client sends a packet after the server reboot, it will receive a FIN segment.
D. The TCP server application on S can listen on P after reboot.
Answer» B. If the client was waiting to receive a packet, it may wait indefinitely.
Discussion
8.

In the congestion avoidance algorithm, the size of the congestion window increases _____ until congestion is detected.

A. Exponentially
B. Additivity
C. Multiplicatively
D. Suddenly
Answer» C. Multiplicatively
Discussion