Stayin' Alive

Understanding TCP keepalive in network systems

This networking question tests your understanding of TCP connection management and the mechanisms that maintain long-lived connections in distributed systems. It is commonly asked at firms building infrastructure, market-data systems, or any platform where persistent connections are critical to reliability.

TCP keepalive is a fundamental concept for anyone working with sockets, protocol design, or system-level networking. The question probes whether you understand not just what the mechanism does, but why it exists—what problem it solves in real deployments where connections may sit idle, firewalls may prune state, or endpoints may fail silently.

• Connection state and timeout behaviour
• Firewall and NAT interaction with long-lived streams
• Detection of peer failure or network partition
• Tuning keepalive parameters for different use cases