Which term describes the initial handshake packet sent to start a TCP connection?

• A. SYN request
• B. ACK
• C. FIN
• D. RST

Answer: (A)

TCP establishes connections with a three-way handshake, starting when the initiator sends a segment with the SYN flag set. This SYN segment is the initial handshake packet, effectively a request to open a connection and to synchronize sequence numbers. That’s why the best description is a SYN (SYN segment) or a SYN request. The other flags come into play in the subsequent steps: the receiver replies with a SYN-ACK to acknowledge and synchronize its side, and the initiator completes the process with a final ACK. FIN and RST are used for closing or resetting connections, not for starting them, and ACK by itself is simply an acknowledgment used after data transfer or in later handshake steps.