Anycast routing / point of presence (PoP)

With anycast, many datacenters announce the same IP address through BGP. Internet routing carries each visitor to the announcement with the best network path, so one address can land in a different point of presence, or PoP, depending on where the request starts. A PoP is simply one of the provider's physical edge locations.

CDNs, global DNS services, and DDoS protection networks use anycast so customers get one stable address without choosing a region themselves. The public resolvers 1.1.1.1 and 8.8.8.8 are the clearest example: one address short enough to memorize, answered by hundreds of machines, none of which you will ever identify. The DNS root servers have worked this way since the early 2000s. If a PoP fails and withdraws its route, traffic can move to another location without changing DNS.

Gotcha: 'nearest' means the route BGP prefers, not the shortest distance on a map. Carrier peering and routing policy can send a visitor past a closer city, and a PoP only helps if the requested content or compute is available there. Anycast gets the request to an edge; it does not make a faraway origin disappear.