Anycast and GeoDNS
Medium Priority18 min readUpdated August 14, 2026
Global services need to answer DNS queries quickly and direct users toward suitable infrastructure. Two mechanisms commonly used for this are Anycast and GeoDNS.
They are often mentioned together, but they solve different problems:
- Anycast lets multiple servers advertise the same IP address. Internet routing selects which server receives a packet.
- GeoDNS returns different DNS answers based on the query's apparent location, network, health state, or policy.
Anycast changes where a packet addressed to one IP is delivered. GeoDNS changes which IP address DNS returns. A production system can use either mechanism independently or combine them.
Keeping those decisions separate is essential when reasoning about latency, failover, caching, and regional traffic.