Exam 312-50v13 Topic 1 Question 394 Discussion

Comprehensive and Detailed Explanation From CEH v13 Guide Topics:
The correct answer is D. SYN. TCP (Transmission Control Protocol) establishes reliable communication between a client and a server through a process known as the three-way handshake. This mechanism ensures that both parties are ready to communicate and agree on sequence numbers before data transfer begins.
The three steps are:
* SYN (Synchronize): The client initiates the connection by sending a TCP packet with the SYN flag set to the server. This packet contains the client ' s initial sequence number (ISN).
* SYN-ACK (Synchronize-Acknowledge): The server responds with a packet containing both SYN and ACK flags. This acknowledges the client ' s request and provides the server ' s own sequence number.
* ACK (Acknowledge): The client sends an ACK packet back to the server, confirming receipt of the server ' s sequence number. At this point, the TCP connection is established and data transmission can begin.
Option A (RST) is used to reset or terminate a connection. Option B (ACK) is used to acknowledge received packets but does not initiate a connection. Option C (SYN-ACK) is sent by the server as the second step of the handshake, not by the client to begin it.
Understanding the TCP three-way handshake is fundamental in CEH network security topics because many attacks, such as SYN flooding, exploit this connection establishment process. Therefore, the client begins the negotiation by sending a SYN packet.