What is the TIME_WAIT state and why is it used after a connection closes?

• A. TIME_WAIT is a state that closes the connection immediately.
• B. TIME_WAIT lasts only for a single MSL.
• C. TIME_WAIT is used to reestablish the connection after closing.
• D. TIME_WAIT ensures delayed segments are not misinterpreted and allows late arriving packets to expire; it lasts twice the Maximum Segment Lifetime (MSL).

Answer: (D)

TIME_WAIT is a waiting period that happens after a TCP connection has been closed by the side that actively ended the connection. During this state, the endpoint holds the connection for twice the Maximum Segment Lifetime (2MSL). This duration is intentional: it lets any delayed or duplicate segments in the network expire, and it prevents those late packets from being misinterpreted as part of a new connection using the same combination of IP addresses and port numbers. By the time the 2MSL window passes, the network has likely discarded stale data, and the port pair is safe to reuse for a new connection.

So, the key idea is to ensure late-arriving packets don’t cause confusion with a future connection, and to provide a window for any stray segments or retransmissions to be safely resolved.