GATE CS 2008 Q17 — Transport Layer: Flow Control, Congestion Control, UDP, TCP, Sockets

To establish a TCP connection, a client-server model uses specific socket system calls. The process of establishing a connection involves the TCP 3-way handshake, which begins with sending a SYN packet.

Let's analyze the role of each system call:

• socket(): Creates an endpoint for communication and returns a socket descriptor. It only allocates local kernel resources and does not generate any network traffic.
• bind(): Associates the socket with a specific local IP address and port number. This is a local operation and does not send any packets over the network.
• listen(): Prepares a bound socket to accept incoming connection requests (making it a passive socket). This is also a local operation on the server side and does not transmit any packets.
• connect(): Called by the client to initiate an active connection to a specified destination IP and port. Invoking connect() triggers the TCP 3-way handshake, causing the client's TCP stack to send the initial SYN packet to the server.

Therefore, the system call that results in sending SYN packets is connect.