Design a replicated key-value store with quorums
Company: Microsoft
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Online Assessment
Design a distributed system that replicates key–value pairs across **multiple replicas**.
The interviewer wants to focus on **replication**, **quorums**, and **failure handling**.
Specify:
- APIs (e.g., `Get(key)`, `Put(key, value)`), consistency goals, and assumptions.
- How data is partitioned and replicated.
- Quorum read/write rules (e.g., N/R/W) and how they affect consistency/availability.
- How you detect and recover from bad nodes, network partitions, and replica lag.
- Handling conflicts (if writes can be concurrent).
Keep it high-level but concrete enough to reason about correctness and trade-offs.
Overview: This question evaluates understanding of replication, quorum protocols, data partitioning, consistency models, failure detection and recovery, and conflict resolution in distributed key–value stores.
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