How does Geo routing work?


I’m interested in Cloudflare’s load balancing service but I’m wanting to understand the technology a bit more. How does a DNS lookup of, say, translate to the IP address nearest to me?

If I type I am directed to an IP that is geographically close to me, instead of being some central server in America, even if I’m in Europe. From what I understand, this isn’t a usual feature of a DNS server.

Is this a special feature of the DNS server? Do all nameservers support this sort of functionality?


Thanks! How does Anycast work with a DNS request? Does the DNS server just return one IP address and that IP address is associated with multiple nodes in the Anycast cluster?

The article should cover that, respectively search engines will have follow up information. It returns an IP address which is mapped to different destinations.

As @sandro mentioned, Cloudflare uses an Anycast network. That means we advertise the same IP address for a website from all of our 175+ datacenters. When a user goes to connect to that IP address, there is an underlying fundamental bit of technology called BGP that network operators use to interconnect/ route traffic between themselves and other networks/network operators on the Internet. Generally this routing is optimized to route to the closest geo, though sometimes it can be optimized for other reasons (cost, performance, geo-political, network architecture).

This would route a user to an appropriate Cloudflare colo. From there, with Geo load balancing, requests would be routed based on the location of that colo in the geo-steering configured in your load balancing policies.


Also see Cloudflare’s page on the technology:

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