What is the standard sequence of packets in the TCP three-way handshake?

• A. SYN, ACK, FIN
• B. ACK, SYN, ACK
• C. FIN, SYN, ACK
• D. SYN, SYN/ACK, ACK

Answer: (D)

TCP connection setup relies on a three-way handshake. The client starts by sending a segment with the SYN flag set to begin the connection and to choose an initial sequence number. The server replies with a segment that has both SYN and ACK flags set, acknowledging the client’s request and providing its own initial sequence number. The client then sends a final segment with the ACK flag set to acknowledge the server’s sequence number, completing the handshake and enabling data transfer. This sequence—SYN, SYN-ACK, ACK—is what establishes the connection. Fin usage appears later for termination, not during setup. Other options try to insert FIN or misorder the flags, which doesn’t match how TCP actually establishes a connection.