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Contrast TCP vs UDP; detect loss

PayPalSoftware Engineer · Technical Screen
MediumSoftware EngineerTechnical ScreenCoding & Algorithms

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This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Contrast TCP vs UDP; detect loss states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

Contrast TCP and UDP in reliability, ordering, congestion control, connection setup, and overhead. How does TCP detect packet loss and trigger retransmission (e.g., timeouts, duplicate ACKs/fast retransmit, and selective acknowledgments)?