I guess this question could be entitiled, how do CDN's work at the DNS level but the real problem I have is that my company has datacenters in three continents and we have to have europe.example.com us.example.com and asia.example.com
CDN's typically send you to the local datacenter I imagine depending on your IP address. This must be a DNS thing where you have the DNS server in USA send you to a USA datacenter for the same example.com DNS lookup?
Am I wrong? If I am wrong about this, how would I do this effectively and if possible without central (non DNS) servers?
Best Answer
The trouble with CDNs is that they don't direct you based on your own IP address - they direct you based on the IP address of your DNS server... That could be completely wrong. And do read Paul Vixie's ACM article, it's bang on the money.
Anyhow, if you've already got
region.example.com
set up and running, you could consider doing an HTTP redirect fromexample.com
to the relevant webserver, based on the client's IP address.That's pretty much what Google does, it's how I end up at
google.co.uk
having typed ingoogle.com
.Do also ensure though that you provide a means for clients to get to the other variations. Clients don't like it when they're forced to a particular site, whether by mistakes in the Geo databases or simply because they actually need to see the site from another region.