Several replicas advertise one prefix; the observing network chooses a usable path according to routing policy. Routing nearest is not a geographic-distance guarantee.

Anycast lets routing select a replica

Anycast gives an address several homes. Multiple sites announce the same prefix, and each network selects a usable path according to routing policy. This article focuses on Internet BGP; local anycast can use an interior routing protocol. A client usually lands at a topologically close replica without first contacting a global load balancer. When one site withdraws its announcement, the control plane can converge on another home. ...

November 1, 2027 · 5 min · XB Field Notes