ITPEC FE Morning October 2022 Question 33

TCP — it slows its sending rate when the network shows signs of congestion.

TCP keeps a congestion window that limits how much unacknowledged data the sender may have in flight. Slow start grows the window quickly from a small value; past a threshold, congestion avoidance grows it linearly. A lost segment (a timeout or three duplicate ACKs) is read as congestion, and the window is cut back. This is separate from flow control, which protects the receiver through the advertised window.

Answer (c)

Why not others:

• •(a) ARP — resolves IP addresses to MAC addresses on a LAN; it carries no data stream to regulate
• •(b) ICMP — reports errors and diagnostics (ping, destination unreachable); it does not control any sender's rate
• •(d) UDP — connectionless, with no acknowledgements and no window, so it sends as fast as the application hands it data; any congestion handling is left to the application

Key rule: Reliability, ordering, flow control and congestion control all belong to TCP; UDP gives them up for low overhead and low latency.

Networks · AI-written, may contain errors