Top 3 Quorum Interview Questions

Browse 3 real-world technical and behavioral interview questions about Quorum. Review scenarios, edge cases, and architectural best practices.

Related Topics:Replication Eventual consistency

Two servers each write a record stamped with its own clock. Why can you not use those timestamps to decide which write happened first, and what do you use instead?

Wall clocks on separate machines disagree by an unbounded amount and can jump backwards, so their timestamps order events by accident rather than by causality. Logical and vector clocks capture what preceded what, quorums give overlap not order, and a lease is safe only with a fencing token.

hardconcept

CAP says you must choose between consistency and availability under a network partition. What are you giving up, concretely?

Under partition you either reject requests on the side that cannot reach a quorum, or serve them and accept divergent replicas that need reconciling. CAP's C is linearisability, not ACID's C, and the choice binds only while partitioned.

hardconcept

Your service writes a record, reads it straight back, and sometimes gets the old value. What is happening and what do you change?

An acknowledged write is only guaranteed on the replicas that acknowledged it, so a read served elsewhere can legitimately return the previous version. Locate the staleness - replica, secondary index or cache - then buy read-your-writes for that operation only, and price what it costs during a partition.

hardscenario