(ISC)2 Certified in Cybersecurity Practice Exam

The TCP Threeway Handshake is a fundamental process used to establish a reliable connection between a client and a server before data transmission begins. The sequence consists of three distinct steps that ensure both parties are ready for communication.

The first step involves the client sending a SYN (synchronize) segment to the server. This indicates that the client wants to establish a connection and is initiating the handshake process.

In the second step, the server responds with a SYN/ACK (synchronize/acknowledge) segment. This conveys that the server has received the initial SYN request from the client and is acknowledging it while also indicating that it is ready to establish the connection.

Finally, the client sends an ACK (acknowledge) segment back to the server, confirming that it has received the server's SYN/ACK response. At this point, a reliable connection is established, and both client and server can begin to communicate.

This orderly process ensures that both sides are synchronized, which is crucial in preventing data loss and maintaining the integrity of the connection. Understanding this sequence is vital in network communication, especially in the context of TCP/IP protocols where reliability is a key component.