Which strategies are used to mitigate hot spots in consistent hashing?

• A. Read replicas copy popular keys, key salting, and adaptive rebalancing.
• B. Only read replicas are used.
• C. Salting keys alone resolves all hot spots.
• D. Rebalancing cannot respond to traffic changes.

Answer: (A)

Mitigating hot spots in consistent hashing relies on spreading load and adapting to changing traffic. In this approach, read replicas distribute the read load of popular items across multiple nodes, so no single node becomes a bottleneck just from reads. Salting keys intentionally adds variability to key names, causing what would be a single hot key to map to multiple distinct hashed keys across different partitions, which spreads the traffic more evenly. Adaptive rebalancing monitors traffic patterns and, when hotspots appear or shift, moves virtual nodes or partitions to different physical nodes to restore balance without overhauling the whole system.

Together, these techniques address hot spots from multiple angles: replication handles read load, salting increases distribution of hot keys, and adaptive rebalancing responds to changing traffic. The other approaches fall short because relying only on read replicas misses write pressure and distribution, salting alone doesn’t cover all traffic dynamics or routing complexities, and rebalancing alone cannot provide the immediate load distribution benefits that replicas and salting offer.