IPA FE Subject A sample Question 28
A question IPA Japan published in 基本情報技術者試験 科目A サンプル問題 問28, translated into English. ITPEC is based on the same exams.
Which of the following is a transport layer protocol that is used when real-time performance is more important than reliability?
Explanation
UDP — the connectionless transport layer protocol, which sends data at once without the acknowledgements and retransmission that make TCP reliable but slower.
UDP sets up no connection, sends no acknowledgements and does not resend lost data, so each datagram goes out with very little delay and overhead. Lost or late packets are simply skipped. That suits voice calls (VoIP), live video streaming and online games, where a late packet is useless anyway, and short exchanges such as DNS queries.
Answer (d)
Why not others:
- •(a) — HTTP is an application layer protocol, and it runs over a reliable transport
- •(b) — IP is a network layer protocol that routes packets; it is not a transport layer protocol
- •(c) — TCP is the transport layer protocol chosen when reliability matters: it confirms delivery, resends lost segments and keeps the order, at the cost of delay
Key rule: At the transport layer, TCP gives reliability (connection, acknowledgement, retransmission, ordering) and UDP gives speed and real-time delivery with none of those.
Networks · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.