Which TCP state indicates an established session and confirmed connection?

The TCP state that indicates an established session and confirmed connection is the ESTABLISHED state. In this state, both the client and server have completed the TCP three-way handshake, which consists of SYN, SYN-ACK, and ACK packets. This handshake ensures that both parties are ready to communicate and have agreed upon the parameters for the connection.

Once the ESTABLISHED state is reached, data can be sent in both directions, enabling full-duplex communication. This is a critical aspect of TCP because it allows for reliable exchange of data, ensuring that packets are acknowledged and that any lost packets can be retransmitted.

In contrast, other states such as FIN_WAIT and TIME_WAIT are related to the process of closing the connection, while LISTEN represents a state where a server is waiting to accept incoming connections but does not yet have an established session. Therefore, the ESTABLISHED state is the only one among the options that signifies that a connection has been fully established and is actively being utilized for data transmission.