Which sequence marks the TCP four-way handshake used to terminate a connection?

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

Answer: (C)

Terminating a TCP connection uses a four-way handshake. One side signals it’s done by sending a segment with the FIN flag set; the other side acknowledges that with an ACK, confirming it saw the request. Then the other side sends its own FIN to indicate it has finished sending, and the first side acknowledges that with a final ACK. So the proper sequence is FIN, ACK, FIN, ACK. The other sequences don’t fit because starting with an ACK isn’t initiating termination, omitting the final ACK leaves the shutdown incomplete, or including a SYN belongs to connection setup rather than teardown.