TCP Service Model

Understanding the TCP service model in network interviews

This question tests your grasp of the fundamental properties and guarantees that TCP provides to applications. It appears in networking rounds at firms that build or operate low-latency trading systems, market data infrastructure, or other performance-sensitive services where engineers must choose between TCP, UDP, and other transport protocols.

To answer correctly, you need to be familiar with TCP's core commitments: ordered delivery, reliability through retransmission, congestion control, and connection-oriented semantics. The question rewards candidates who can distinguish TCP's actual service model from common misconceptions or oversimplifications, and who understand why these guarantees matter for system design.

• Reliability and in-order delivery semantics
• Connection establishment and teardown (three-way handshake, FIN sequences)
• Flow control and congestion-avoidance mechanisms
• Trade-offs between TCP and connectionless alternatives