Which of the following system calls results in the sending of SYN packets?

Answer: connect

Why: The connect system call performs an active TCP open. When connect is called on a TCP socket, the kernel sends a TCP SYN packet to the remote endpoint to start the three-way handshake.

• socket: creates a local endpoint (socket descriptor); it does not transmit packets.

• bind: assigns a local IP address and port to a socket; it does not initiate a TCP connection.

• listen: places a socket into passive mode so it can accept incoming connections; it does not send SYN packets.

• connect: performs an active open and causes the kernel to send a TCP SYN to initiate the three-way handshake.