Which of the following correctly pairs a packet type with its meaning?

• A. SYN: Initiate a connection.
• B. SYN/ACK: End the connection
• C. ACK: Initiate a connection
• D. FIN: Acknowledges data received

Answer: (A)

Understanding TCP flags and how the handshake works is the key idea. A SYN flag is used to start a TCP connection: a client sends a segment with SYN to begin the session, indicating a request to establish communication and providing an initial sequence number. The other side replies with a segment that has SYN and ACK set, acknowledging the request and agreeing to open the connection. The initiator then sends a final ACK to complete the handshake and establish the connection. That makes the pairing of SYN with initiating a connection the correct match.

SYN/ACK is part of the handshake process, not something that ends a connection. ACK by itself is just an acknowledgment of received data within an already established connection, not a initiation. FIN signals the intent to close the connection and is part of the closing sequence, not an initiation.