Project ForgeSuppose 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?
I. If the sequence number of a segment is m, then the sequence number of the subsequent segment is always m+1. II. 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. III. The size of the advertised window never changes during the course of the TCP connection. IV. The number of unacknowledged bytes at the sender is always less than or equal to the advertised window.
- AIII only
- I and III only
- CI and IV only
- DII and IV only
Explanation
I is FALSE: TCP sequence numbers advance by the number of DATA BYTES sent, not by 1 per segment. II is TRUE: retransmission timeout is always set ≥ estimated RTT (with a safety margin) so retransmissions aren't premature. III is FALSE: the advertised window changes dynamically as the receiver's buffer availability changes. IV is TRUE: TCP's flow control guarantees unacknowledged bytes never exceed the advertised window. So the FALSE statements are I and III.
Source: GATE CS 2015 (Session 1 / 7th Feb Shift 1) (2015)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.