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312-50V13 · Question #54

The establishment of a TCP connection involves a negotiation called three-way handshake. What type of message does the client send to the server in order to begin this negotiation?

The correct answer is B. SYN. To initiate a TCP three-way handshake and establish a connection, the client first sends a Synchronization (SYN) message to the server.

Submitted by minji_kr· Mar 6, 2026Scanning Networks

Question

The establishment of a TCP connection involves a negotiation called three-way handshake. What type of message does the client send to the server in order to begin this negotiation?

Options

  • AACK
  • BSYN
  • CRST
  • DSYN-ACK

How the community answered

(40 responses)
  • A
    3% (1)
  • B
    95% (38)
  • D
    3% (1)

Why each option

To initiate a TCP three-way handshake and establish a connection, the client first sends a Synchronization (SYN) message to the server.

AACK

An ACK (Acknowledgement) flag is used to acknowledge receipt of data or previous SYN/SYN-ACK packets, not to initiate a connection.

BSYNCorrect

In the TCP three-way handshake, the client initiates the connection by sending a Segment with the SYN (Synchronization) flag set to the server, indicating its desire to establish a connection. This SYN packet includes an initial sequence number.

CRST

An RST (Reset) flag is used to immediately terminate a TCP connection due to an error or an abnormal situation.

DSYN-ACK

A SYN-ACK message is the server's response to the client's initial SYN, acknowledging the client's request and simultaneously sending its own SYN.

Concept tested: TCP three-way handshake initiation

Source: https://learn.microsoft.com/en-us/windows-server/networking/technologies/network-subsystem/tcpip/tcp-ip-fundamentals-for-windows-10#the-tcp-three-way-handshake

Topics

#TCP/IP#Three-way handshake#SYN packet#Network protocols

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