What does a SYN/ACK indicate?

• A. The server is refusing a connection.
• B. The server is accepting the connection.
• C. Data transfer has begun.
• D. The connection is closed.

Answer: (B)

In TCP, opening a connection is a three-way handshake. The client starts with a SYN to request a connection, and the server replies with a SYN-ACK to show it received that request and is willing to establish the connection. The SYN flag indicates synchronization of sequence numbers, and the ACK confirms the receipt of the client's SYN. This means the server is accepting the connection and the session is in progress, but actual data transfer begins only after the client replies with the final ACK to complete the handshake. If the server isn’t willing to connect, you wouldn’t see a SYN-ACK; a reset or a different response would occur instead.