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+1 vote

Consider a scenario where UDP receiver computes the Internet checksum for the received UDP segment and finds that it matches the value carried in the checksum field.

Which of the statement below is true with respect to the above scenario?

  • Receiver is absolutely sure that no bit errors have occurred.
  • If the receiver is TCP instead of UDP, the receiver is still absolutely sure that no bit errors have occurred.
  • UDP receiver is absolutely sure about no error. But if it’s a TCP receiver it won’t be.
  • Both TCP and UDP receivers will not be absolutely sure about no error

Answer given is D but I feel it should be B because Tcp checksum is calculated on data and header both.

asked in Computer Networks by Boss (5.3k points) 4 56 138 | 192 views

2 Answers

+1 vote
checksum shud be again calculated on pseudo header. only then receiver can be sure that no error occured. (incase of both TCP and UDP)
answered by Veteran (12.5k points) 12 52 155

As it is Internet checksum(IP checksum) so we can't be so sure about any error.To be sure we have to do double checking using TCP checksum.
0 votes
answer is D

since the data received is from the network layer to transport layer, and we know at network layer we have IP which uses checksum at header there is lots of probability that data might be corrupted. therefore either UDP or TCP they have to perform the checksum then only they can be sure about it.

better to see the format of IP and compare it with UDP and TCP. you will find that in IP we have only header checksum while in TCP/UDP we have checksum for header and data both.
answered by Active (1.8k points) 1 4 18

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