Which statement best describes the purpose of a TCP handshake?

• A. To encrypt data during transmission.
• B. To map a host to an IP address.
• C. To establish a reliable connection by synchronizing sequence numbers and acknowledging data transfer.
• D. To terminate a connection.

Answer: (C)

The handshake’s purpose is to establish a reliable connection before any data is exchanged. In TCP, the three-step exchange (SYN, SYN-ACK, ACK) lets both ends synchronize their sequence numbers and confirm each side is ready to receive data. This setup ensures that every byte can be tracked, acknowledged, and, if needed, retransmitted, so data arrives in order and without loss. It also negotiates initial parameters like flow control, so both sides know how much data can be in flight.

This isn’t about encryption, which is handled by separate security layers, nor about mapping hostnames to IP addresses, which is DNS’s job. It’s also not about ending a connection—that happens later with a termination sequence. The handshake specifically primes the connection for reliable data transfer by aligning sequence numbers and acknowledgments.