GATE CSE 2015 Set 1 | Question: 1‏9

Question

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.

• A. III only
• B. I and III only
• C. I and IV only
• D. II and IV only

Comments

First of all thank you so much for your response, I appreciate it.

So I asked wether saying sender window size = no of acknowledge bytes at that instance is correct as you explained.

I got this doubt because I thought that sender could have any amount of data to send as it depends on application program, but turns out that amount of data sender could send constrained by window size is referred as “unacknowledged bytes at the sender” and this resolves all the quiries. Thanks again!

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@codeitram ..Just to be sure for your doubt  …

unacknowledged bytes = sender window size

equal to is not correct here……

it should be <=

reference:

 LFS(sequence number of last frame sent)

LAR(last sequence number for which acknowledgment is received)

 

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For more understanding, here is a link to a short video lecture by IITB professor Mrs Kameswari.

https://www.youtube.com/watch?v=2uMolhFyH9U&list=PL-bZp8Qhr-SZG08n3IeXT8R5hafSg_jIv&index=14.

Answer 1

TCP assigns a sequence number for 8 bit (1 byte)character or 8 Byte character ?

Comments

Every byte (8 bit)