Consistent Hashing

A hashing strategy that maps both keys and servers onto a circular hash ring, so that adding or removing a server causes only a small fraction of keys to be remapped rather than redistributing all keys. In load balancing, consistent hashing can route requests with the same client IP or request attribute to the same backend without sticky session cookies. It is also foundational in distributed caches (Memcached, Redis Cluster), key-value stores, and CDN origin selection. Virtual nodes (vnodes) per server improve key distribution uniformity and handle heterogeneous server capacities.