What mechanism does TCP use to establish a connection between two endpoints?

What mechanism does TCP use to establish a connection between two endpoints?

• A. Three-way handshake
• B. Four-way handshake
• C. Simple greeting
• D. Direct connect

Answer: (A)

TCP establishes a connection through a three-step exchange that synchronizes both ends and gets the session ready for data transfer. The client starts by sending a segment with the SYN flag set and an initial sequence number it chooses. The server replies with a segment that has both SYN and ACK flags set, acknowledging the client’s sequence number and supplying its own initial sequence number. Finally, the client sends back a segment with the ACK flag, acknowledging the server’s sequence number. Once this three-way handshake completes, both sides know the connection is ready and they have agreed on initial sequence numbers, enabling reliable, ordered data transfer. This approach matters because it confirms both sides are present and prepared, negotiates the starting points for sequencing, and prevents confusion from old or duplicated connection attempts. The other options don’t fit: a four-way handshake is used for terminating a connection gracefully, while a simple greeting or a direct connect isn’t how TCP reliably establishes a session.

TCP establishes a connection through a three-step exchange that synchronizes both ends and gets the session ready for data transfer. The client starts by sending a segment with the SYN flag set and an initial sequence number it chooses. The server replies with a segment that has both SYN and ACK flags set, acknowledging the client’s sequence number and supplying its own initial sequence number. Finally, the client sends back a segment with the ACK flag, acknowledging the server’s sequence number. Once this three-way handshake completes, both sides know the connection is ready and they have agreed on initial sequence numbers, enabling reliable, ordered data transfer.

This approach matters because it confirms both sides are present and prepared, negotiates the starting points for sequencing, and prevents confusion from old or duplicated connection attempts. The other options don’t fit: a four-way handshake is used for terminating a connection gracefully, while a simple greeting or a direct connect isn’t how TCP reliably establishes a session.