System design — the round that rewards a calm, structured approach over memorised answers. Guided order first, full note grid below.
Learn in this order
- Basics — the framework: requirements → estimation → high-level → deep-dive → trade-offs
- Consistent Hashing — the one algorithm that reliably comes up
- Trade Offs — CAP, consistency vs. availability, SQL vs. NoSQL
- Load Balancing & Sharding — build next
- Case Studies — URL shortener, news feed, chat (build next)
The move
Interviewers score how you reason, not whether you recall an answer. Always
start by clarifying requirements and estimating scale — never jump to a diagram.