Transport Layer

Question 11

Packets of the same session may be routed through different paths in

• TCP, but not UDP

• TCP and UDP

• UDP, but not TCP

• Neither TCP, nor UDP

Question 12

The maximum window size for data transmission using the selective reject protocol with n-bit frame sequence numbers is:

• 2^n
• 2^(n-1)
• 2^n – 1
• 2^(n-2)

Question 13

Which of the following functionalities must be implemented by a transport protocol over and above the network protocol ?

• Recovery from packet losses

• Detection of duplicate packets

• Packet delivery in the correct order

• End to end connectivity

Question 14

Which of the following is NOT true about User Datagram Protocol in transport layer?

• Works well in unidirectional communication, suitable for broadcast information.

• It does three way handshake before sending datagrams

• It provides datagrams, suitable for modeling other protocols such as in IP tunneling or Remote Procedure Call and the Network File System

• The lack of retransmission delays makes it suitable for real-time applications

Question 15

Suppose two hosts use a TCP connection to transfer a large file. Which of the following statements is/are False with respect to the TCP connection?

1. If the sequence number of a segment is m, then the sequence 
   number of the subsequent segment is always m+1.
2. If the estimated round trip time at any given point of time
   is t sec, the value of the retransmission timeout is always
   set to greater than or equal to t sec.
3. The size of the advertised window never changes during the 
   course of the TCP connection.
4. The number of unacknowledged bytes at the sender is always 
   less than or equal to the advertised window 

• 3 only
• 1 and 3 only
• 1 and 4 only
• 2 and 4 only

Question 16

A link has a transmission speed of 10⁶ bits/sec. It uses data packets of size 1000 bytes each. Assume that the acknowledgment has negligible transmission delay, and that its propagation delay is the same as the data propagation delay. Also assume that the processing delays at nodes are negligible. The efficiency of the stop-and-wait protocol in this setup is exactly 25%. The value of the one-way propagation delay (in milliseconds) is ___________.

• 4
• 8
• 12
• 16

Question 17

Identify the correct order in which a server process must invoke the function calls accept, bind, listen, and recv according to UNIX socket API.

• listen, accept, bind recv
• bind, listen, accept, recv
• bind, accept, listen, recv
• accept, listen, bind, recv

Question 18

Assume that the bandwidth for a TCP connection is 1048560 bits/sec. Let α be the value of RTT in milliseconds (rounded off to the nearest integer) after which the TCP window scale option is needed. Let β be the maximum possible window size with window scale option. Then the values of α and β are.

• 63 milliseconds 65535 × 2¹⁴

• 63 milliseconds 65535 × 2¹⁶

• 500 milliseconds 65535 × 2¹⁴

• 500 milliseconds 65535 × 2¹⁶

Question 19

Consider the following statements.

I. TCP connections are full duplex.
II. TCP has no option for selective acknowledgment
III. TCP connections are message streams.

• Only I is correct
• Only I and II are correct
• Only II and III are correct
• All of I, II and III are correct

Question 20

Consider a network connecting two systems located 8000 kilometers apart. The bandwidth of the network is 500 × 10⁶ bits per second. The propagation speed of the media is 4 × 10⁶ meters per second. It is needed to design a Go-Back-N sliding window protocol for this network. The average packet size is 10⁷ bits. The network is to be used to its full capacity. Assume that processing delays at nodes are negligible. Then, the minimum size in bits of he sequence number field has to be ________.

• 2
• 4
• 8
• 16