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System Design, Beginner
Start with the client-server model and the handful of building blocks — load balancers, databases, caches, APIs — that every design question reuses.
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The mental model
18 min read
The order I'd read them in
About 2 h 25 min of reading. Tick off what you've read, it is remembered on this device.
- What system design interviews testThere is no answer key — the interviewer is scoring how you got there, not where you landed.
- Client-server basicsA senior candidate can narrate everything between the keypress and the pixel — and knows what each hop costs in milliseconds.
- Scaling: vertical vs horizontalBuy a bigger box or buy more boxes — and one modern box is far bigger than the candidate who instantly reaches for a cluster believes.
- Databases in system designThe choice is decided by access pattern and consistency need — "SQL doesn't scale" is a claim that will cost you the interview.
- Caching fundamentalsA cache is one bet placed at six distances — and the interesting number is never the hit rate, it's the miss rate.
- APIs & communicationThe API is the coupling surface — every round trip, every version and every retry is a design decision someone will live with for years.
- Walkthrough: a URL shortenerThe full 45-minute arc on the classic warm-up question — where every number is shown, every choice is defended, and the trap is the click counter.
Practice at this level
No exercises tagged for this level yet. The ones on each chapter above still work.