LISTEN state in a TCP socket refers to:
A TCP socket is ready and is listening for incoming connections
A synchronization request has been sent
The socket has received a synchronization request
All of the above
The Correct Answer and Explanation is :
The correct answer is:
A TCP socket is ready and is listening for incoming connections.
Explanation:
In the context of TCP (Transmission Control Protocol), the “LISTEN” state is a crucial part of the process in which a server socket waits for incoming connection requests from clients. This state is part of the connection establishment process defined by the TCP three-way handshake. Let’s break it down step by step:
- TCP Handshake Process:
When a client wants to establish a connection with a server, it must go through a series of steps known as the three-way handshake:
- SYN (Synchronize): The client sends a SYN message to the server to request a connection.
- SYN-ACK (Synchronize-Acknowledge): The server responds by acknowledging the SYN request with a SYN-ACK message.
- ACK (Acknowledge): The client sends an ACK message, confirming the connection. After this, the connection is established, and data can be transferred.
- The LISTEN State:
Before a server can accept any connections, its TCP socket needs to enter the LISTEN state. This happens when the server is ready to accept incoming connection requests. Here’s what occurs in detail:
- The server creates a socket, binds it to a specific IP address and port, and then sets it to the LISTEN state. This means that the server is waiting for incoming SYN requests from clients, signaling that the server is ready to accept a connection.
- The server listens for incoming connection requests but doesn’t establish a full connection at this stage.
- The Role of the LISTEN State:
The socket in the LISTEN state does not accept the connection immediately; it simply acknowledges that the server is available and ready to accept connection requests. Once the server receives a SYN request from a client, it responds with a SYN-ACK (the second part of the handshake). After the full handshake is completed, the socket transitions from the LISTEN state to an ESTABLISHED state, where communication can begin.
In conclusion, the LISTEN state indicates that the server socket is ready to receive incoming connection requests. This is a key step in the process of setting up a reliable TCP connection between a client and server.