Compare TCP and UDP at a high level
Reported in Improbable European engineering loops. Networking basics question covering transport-layer reliability and use cases.
Interview scenario
Often asked in Improbable loops at European offices (London, Berlin, Amsterdam, Paris, Stockholm, Dublin, and remote EU). Prepare a clear spoken answer plus key trade-offs.
Model answer
Try answering aloud first
Cover trade-offs, structure, and a concrete example before revealing the baseline response.
How to frame this at Improbable: Connect your answer to measurable impact, clarity of thought, and trade-offs the team cares about. Below is a strong baseline response you can adapt with your own project examples.
TCP (Transmission Control Protocol) is connection-oriented and reliable. It guarantees ordered delivery, retransmits lost packets, and uses flow control and congestion control. Overhead includes three-way handshake, acknowledgments, and sliding windows.
UDP (User Datagram Protocol) is connectionless and best-effort. It sends datagrams without guaranteed delivery or ordering—lower latency and header overhead, but the application must handle loss if needed.
Use TCP for HTTP, file transfer, and any scenario where correctness beats raw speed. Use UDP for live video, gaming, DNS, and metrics where occasional loss is acceptable and timeliness matters more than completeness.
Bonus points: mention QUIC (HTTP/3) combining UDP transport with built-in encryption and multiplexing, reducing head-of-line blocking compared to TCP.
Discussion
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