A TCP server application is programmed to listen on port number P on host S. A TCP client is connected to the TCP server over the network.
Consider that while the TCP connection was active, the server machine S crashed and rebooted. Assume that the client does not use the TCP keepalive timer. Which of the following behaviors is/are possible?
(A) If the client was waiting to receive a packet, it may wait indefinitely
(B) The TCP server application on S can listen on P after reboot
(C) If the client sends a packet after the server reboot, it will receive a RST segment
(D) If the client sends a packet after the server reboot, it will receive a FIN segment
Answer: (A) (B) (C)
Explanation: A keepalive timer is used to prevent a long idle connection between two TCPs.
So, in absence of TCP keepalive timer, option (A) is correct.
The TCP server application on S can listen on P after reboot. True because session is still there. Option (B) is correct.
An abrupt connection release is carried out when a RST segment is sent. Option (C) is correct.
A TCP connection is terminated using FIN segment where FIN bit is set to 1. Option (D) is false.