CCIE Routing and Switching (legacy) — Question 20

Which TCP feature allows a client to request a specific packet that was lost?

Answer options

• A. fast recovery
• B. selective acknowledgement
• C. flow control
• D. sliding window

Correct answer: A

Explanation

The correct answer is A, as fast recovery is part of the TCP congestion control mechanism that helps quickly recover from packet loss. The other options do not specifically address the ability to request lost packets; for example, selective acknowledgement (B) is about acknowledging received packets, flow control (C) manages data transmission rates, and sliding window (D) is a technique for controlling the flow of packets.