# A Practice Plan and Checklist — System Design Interview Prep

Source: https://www.skillbyai.com/en/system-design-interview/v-practice

> Deliberate repetition.

## Practise out loud, with a timer

Pick a set of classic problems (URL shortener, rate limiter, news feed, chat, notifications, proximity service, web crawler, key-value store, video streaming, payment system) and practise each aloud in 45 minutes, ideally with a peer playing interviewer. Afterwards, compare with published designs, note gaps, and redo weak problems a week later. Review the building blocks and estimation maths until they come quickly.

## Interview checklist

Run through it during practice sessions.

```text
[ ] clarified functional + non-functional requirements; stated assumptions
[ ] estimated QPS (avg/peak), storage, cache size where it mattered
[ ] defined API and data model with access patterns
[ ] drew an end-to-end high-level design before deep dives
[ ] chose storage by access pattern; shard key and replication explained
[ ] caching, queues, idempotency and rate limiting where needed
[ ] identified bottlenecks, hot keys and single points of failure
[ ] explained trade-offs and rejected alternatives
[ ] covered monitoring and failure handling
[ ] finished with a short summary
```

## Record yourself

Listening to a recorded practice run reveals rambling, silent stretches and skipped steps.

**Quiz:** Which practice habit is most effective?

- [ ] Reading designs without practising
- [ ] Memorising one diagram per problem
- [x] Timed, out-loud mock interviews followed by gap review
- [ ] Only studying vendor documentation

*Answer:* Timed, out-loud mock interviews followed by gap review. Practise the conversation, not just the content.