System designMediumsd-p008

Subject CachingLevel Mid–Senior~45 minCommon in Distributed systems interviewsIndustries Technology, Software development

Question

Design a distributed in-memory cache (like Memcached/Redis at scale) used as a read-through layer in front of a database. Address sharding, evictions, and hot keys.

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.