In TCP Connection Termination, when client enters in TIME_WAIT state means the client waits for a period of time equal to double the maximum segment life (MSL) time, to ensure the ACK it sent was received.
(I read above from a book computer networking by kurose and also given in following URL http://www.tcpipguide.com/free/t_TCPConnectionTermination-2.htm )
But how it was detected if last ACK(send by client as a response to server FIN) lost?
Best Answer
It's essentially a "don't care". The wait period is to prevent confusion with subsequent connections. Why is the final ACK then sent? It helps clear connection resources on the other side.