4.Distributed Systems

Redis Cluster sharding with 16,384 hash slots, client redirection, hash tags, resharding, replica failover, and its consistency and multi-key constraints.

Redis Sentinel monitoring and failover for primary-replica deployments, including subjective/objective down states, quorum, failover authorization, promotion, and remaining consistency limits.

Redis primary-replica replication, full and partial synchronization, replication backlog, stale replica reads, and asynchronous failure semantics.