Which netstat state indicates the socket is listening for incoming connections?

• A. LISTEN
• B. ESTABLISHED
• C. CLOSED
• D. SYN_SENT

Answer: (A)

In TCP, a server socket that has been bound to a local address and port and is waiting for new connections sits in the LISTEN state. netstat reports LISTEN for those sockets, indicating they are ready to accept incoming connections. An ESTABLISHED state means there is an active TCP connection between two endpoints. CLOSED means the socket is not open or a connection has been closed. SYN_SENT means a connection attempt has been initiated and a SYN has been sent, but the handshake hasn’t completed yet. So, when you want to know which socket is waiting for incoming connections, the LISTEN state is the right indicator.