A Four-Step Framework

Spend time deliberately

A widely used structure: (1) clarify requirements and scope (about 5 to 10 minutes), (2) propose a high-level design with APIs, data model and main components, agreeing it with the interviewer (10 to 15 minutes), (3) deep dive into the most interesting or risky parts, such as scaling the hot path, data partitioning or consistency (15 to 20 minutes), and (4) wrap up with bottlenecks, failure handling, monitoring and possible improvements. Estimates fit into step 1 or 2 when they influence decisions.

A whiteboard template

A layout to reuse in every interview.

1. REQUIREMENTS          functional: ...    non-functional: scale, latency, availability, consistency
2. ESTIMATES             QPS (avg/peak), storage, bandwidth, cache size
3. API                   POST /v1/urls {long_url} -> {code};  GET /{code} -> 301
4. DATA MODEL            table/collection, keys, access patterns
5. HIGH-LEVEL DESIGN     client -> LB -> services -> cache -> DB / queue -> workers
6. DEEP DIVES            partitioning, hot keys, consistency, failure modes
7. WRAP UP               bottlenecks, monitoring, trade-offs, future work

Check in at each step

Ask "does this direction work for you?" before deep dives; interviewers often steer you towards what they want to assess.

Quick check: What should come before drawing components?

• Clarifying requirements and scope
• Choosing a database vendor
• Writing code
• Designing the monitoring dashboard