Which statement best describes UDP in relation to reliability?

Which statement best describes UDP in relation to reliability?

• A. It does not guarantee reliability and may deliver packets out of order.
• B. It always ensures in-order delivery.
• C. It uses acknowledgment to guarantee delivery.
• D. It enforces flow control.

Answer: (A)

UDP is a connectionless, best-effort transport protocol that does not provide reliability. There is no acknowledgment, no retransmission, and no sequencing guarantees, so datagrams can arrive out of order or be lost. Because of this, UDP does not enforce flow control and leaves reliability and ordering to the application or higher-layer protocols. That’s why the statement describing UDP in relation to reliability is that it does not guarantee reliability and may deliver packets out of order. If reliability is required, the application must implement it itself or use a protocol like TCP.

UDP is a connectionless, best-effort transport protocol that does not provide reliability. There is no acknowledgment, no retransmission, and no sequencing guarantees, so datagrams can arrive out of order or be lost. Because of this, UDP does not enforce flow control and leaves reliability and ordering to the application or higher-layer protocols. That’s why the statement describing UDP in relation to reliability is that it does not guarantee reliability and may deliver packets out of order. If reliability is required, the application must implement it itself or use a protocol like TCP.