URL shortener
Design a small URL shortener for an internal company tool that handles about 1,000 new links per day and a few thousand redirects per day. A user pastes a long URL and gets back a short code; visiting the short code redirects to the original. The system is read-heavy (far more redirects than creates) and links never expire. Walk through the components, the data model, and how you generate short codes.
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.
Clarify3:00 left
Estimate3:00 planned
Design8:30 planned
Deep dive6:30 planned
Failure4:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.