Anycast is such an interesting technology. We use it on our DynECT Platform to dramatically speed delivery of DNS resolution for our customers’ end users. The theory is that geographically-dispersed DNS servers are assigned the same IP address. Normally, you’d never do this (IPs are supposed to be unique), but it works due to some inherent behaviors in the Internet’s main routing system, called Border Gateway Protocol, or BGP, for short. What happens is that Internet core routers, when given two routes to the same IP address, forward the DNS queries to the closest site. By using geographically proximate sites to those querying our DNS servers, we speed provide very fast DNS resolution. When DNS lookups are completed faster, web sites load faster.
There are many providers that say they have an anycasted DNS network. True, two computers that have the same address and are routed in this fashion is technically anycast. Does this level of anycast have any benefit in terms of a speed up for end users? We think not.
We believe that anycast is when there is a network of servers deployed in major populations around the world. That way, significant portions of the Internet experience a real speed up. If you have anycast deployed solely in one country, you might as well consider yourself unicast to the rest of the world. These providers do themselves a disservice by unnecessarily complicating their networks for little performance gain. So, if you’re considering an anycast DNS provider, be sure to ask for a list of locations that they’re deployed in and why they chose those spots. Here’s our list, in case you were wondering:
- Boston, MA, USA
- Chicago, IL, USA
- Palo Alto, CA, USA
- Ashburn, VA, USA
- London, UK
- Amsterdam, Netherlands
- Frankfurt, Germany
- Hong Kong, Hong Kong
That’s 8 major population centers around the world, with less than 50 milliseconds of DNS lookup latency for most world population centers. We plan to expand to more cities soon, and since you’re reading this, here’s a secret – Tokyo or Sydney is next.