System designHardsd-g698

Subject P2p file transfer protocolLevel Senior–Staff~45 minCommon in Networking & APIs interviewsIndustries Technology, Software development

Question

Design a peer-to-peer file-transfer system (think a BitTorrent-style or WebRTC-datachannel-based distribution) for shipping large build artifacts (1–20 GB) to thousands of machines inside corporate networks, minimizing the load on a central origin. You need integrity guarantees, resumable transfers, and to work across NATs/firewalls. How do peers find each other, exchange chunks, and what's the central server still for?

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.