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Understanding TCP keep-alive and connection monitoring

This is an easy networking question that tests your grasp of how TCP maintains long-lived connections in real-world systems. It covers a practical mechanism that appears in both interview settings and production code, especially in low-latency and distributed systems where silent connections are common.

The question focuses on the initiation of keep-alive activity—how TCP signals the desire to verify that a peer is still reachable when no application data has been exchanged for some time. Understanding this mechanism is essential for building robust network applications, since connection failures can be masked by the absence of traffic, leading to stalled or hung processes.

• TCP connection state and idle detection
• Socket-level configuration and options
• Distinction between application-level and protocol-level heartbeats
• Handling network failures and unreachable peers