How does Geo routing work?

#1

Hello,

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, google.com translate to the IP address nearest to me?

If I type google.com 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

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#2
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#3

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?

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#4

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

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#5

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.

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#6

Also see Cloudflare’s page on the technology:

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