TCP Socket

Understanding TCP socket identification in networks

This is an easy networking question that tests whether candidates understand the fundamental addressing scheme underpinning TCP communication. It appears in interviews where systems knowledge matters—particularly at firms building trading infrastructure, market data systems, or any platform handling high volumes of network traffic.

The question asks you to identify which pieces of information the operating system and network stack use to distinguish one TCP connection from another. The answer requires you to think about what happens at both endpoints of a connection and how the kernel tracks active sockets. This is foundational knowledge for debugging network issues, understanding port exhaustion, and reasoning about connection limits in production systems.

• The role of IP addresses and port numbers in socket identity
• Directionality: client vs. server perspective
• How the OS uses this tuple for socket lookup and multiplexing