System designEasysd-g554

Subject Session managementLevel Entry–Mid~25 minCommon in Distributed systems interviewsIndustries Software development, Technology

Question

Design a session store for a web app that runs on several server instances behind a load balancer. After a user logs in, every subsequent request must know who they are. Sessions should expire after a period of inactivity. Describe where session data lives and how a request looks up the logged-in user fast.

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.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.