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Network Protocols and Packet Switching: Question 9

Syllabus 14.1, 14.2

Multiple choice A2 1 mark

A network technician has written four statements about protocols and switching methods on the internet, to test new trainees' understanding. Exactly one of the four statements is correct.

Which statement is correct?

Choose an answer to check it, then compare with the worked solution below.
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Worked solution

Why A is correct

Packet switching’s shared links can carry packets belonging to many different communications at once, since each communication only needs to send its packets as and when it actually has data ready, rather than holding an entire path reserved for itself the whole time. This makes packet switching well suited to a network of many pairs of devices exchanging short, bursty messages, because the network’s capacity is used efficiently across all of them rather than being tied up by any one communication that is not constantly transmitting. This is a correct, general comparison of when packet switching suits the traffic pattern better than circuit switching, so A is correct.

Why the other options are wrong

  • B is incorrect: FTP and HTTP are both Application-layer protocols, not Transport-layer protocols. Reliable delivery of data between the correct application on each host, which FTP and HTTP both rely on, is the job of the Transport layer underneath them, not something FTP or HTTP provide themselves.
  • C is incorrect: once a circuit-switched path has been set up, it is reserved exclusively for the call it was created for. No other device or call is able to share that same path, in any proportion, while the original call is still using it. This is precisely why circuit switching can waste capacity when a reserved path is not being fully used.
  • D is incorrect: IMAP and POP3 are both protocols used to retrieve/manage stored mail that is already waiting on a mail server, not to send a newly composed message. Sending a newly composed message from a client to its first mail server is the job of SMTP.

Final answer

  • A. A network of short, bursty messages between many different pairs of devices is generally better suited to packet switching than circuit switching, because packet switching shares its links between many communications rather than reserving a whole path for one.