GeoDNS allows you to return different zone files depending on the location of the source query. If you are in New York, query for foo.cdnbar.com, and the namese

GeoDNS allows you to return different zone files depending on the location of the source query. If you are in New York, query for foo.cdnbar.com, and the nameserver serving that CDN is geo-aware, you might get a northeast-based IP. Google then caches that. 5 minutes later, I, in Arizona, come along and ask for foo.cdnbar.com, and it just gives me your northeast-based IP, meaning I have an extra four hops and 3000 miles for my packets to travel than if I'd pulled that IP off of my ISP's DNS.