In networking, latency is the delay between a request and the first bit of data arriving.

• A. The delay before data starts moving after a request is made.
• B. The maximum capacity of a link.
• C. The amount of data that can be stored in a router buffer.
• D. The overall data rate achieved during transmission.

Answer: (A)

Latency is the time it takes from when a request is issued to when the first bit of data arrives. This delay includes propagation time as well as any processing and queuing delays along the path. The option describing the delay before data starts moving after a request matches this idea exactly, since it focuses on that initial wait before transmission begins. The other ideas refer to different concepts: bandwidth is the maximum data rate a link can carry, buffering is how much data a device can store temporarily, and throughput is the actual data transfer rate achieved, which can be limited by latency and other factors.