Code Room
On-callHardoc-g124
Subject Inconsistent replicasLevel Senior–Staff~45 minCommon in Databases & SQL · Networking & APIs · Distributed systems interviewsIndustries Technology, Software development

Question

Search results are inconsistent: the same query returns different document sets on consecutive requests, and some recently-indexed docs appear then disappear. Started after a 14:05 network blip between two availability zones. Dashboards: the Elasticsearch cluster shows two nodes each claiming to be master (cluster state diverged), the AZ-A and AZ-B node groups can't see each other, indexing requests succeed in BOTH partitions, and shard allocation differs between the two views. The cluster has 4 master-eligible nodes (no dedicated tiebreaker). How do you triage this split-brain, stop divergence, and reconcile the data?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

Diagram & narrate the incident
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Run or narrate your approach, then ask the coach.