Delayed Acknowledgments

Understanding TCP's delayed acknowledgment mechanism

This is a medium-difficulty networking question that tests your understanding of flow control and efficiency trade-offs in TCP. It appears in interviews at firms that build trading infrastructure, market-data systems, or other latency-sensitive applications where knowledge of protocol behaviour is critical to diagnosing performance issues.

The question asks you to explain the reasoning behind a specific TCP optimisation—one that affects how the protocol handles the return path. Rather than requiring calculation or code, it probes whether you understand the design decisions embedded in the TCP/IP stack and can articulate the problem that this mechanism solves.

• TCP flow control and sliding windows
• Bandwidth utilisation versus acknowledgment overhead
• Trade-offs between responsiveness and efficiency
• How protocol behaviour interacts with application patterns