Which of the following socket API functions converts an unconnected active TCP…

Answer: listen

Explanation: The listen function marks a previously created and bound TCP socket as passive, enabling the system to queue incoming connection requests so the server can accept them.

Typical server call sequence:

1. Create a socket with socket().

2. Bind the socket to a local address and port with bind().

3. Call listen(backlog) to convert the socket into a passive listening socket.

4. Use accept() to accept queued incoming connections and obtain a new connected socket for each client.

Brief function roles:

• connect: used by a client to establish an active connection to a remote server.

• bind: assigns a local address/port to a socket; required before listening but does not make the socket passive.

• listen: converts the socket into a passive listening socket and enables queuing of incoming connection requests.

• accept: accepts a queued connection on a listening socket and returns a new connected socket for communication.