Posted On: Apr 2, 2014
We’re excited to let you know that Amazon CloudFront has added support for EDNS-Client-Subnet. With this enhancement, Amazon CloudFront now provides even better routing, hence improving performance for your end users who use Google Public DNS or Open DNS resolvers.
Amazon CloudFront automatically routes requests for your content to the optimal edge location by looking at the IP address of the resolver making the DNS query. We do this because DNS resolvers are typically a good proxy for an end user's location. However, in some cases, your end users may be using DNS resolvers that are far from their geographic location and in those cases, end user requests may be routed to an Amazon CloudFront edge location that isn’t optimal for your end user. By supporting EDNS-Client-Subnet, Amazon CloudFront can now route requests to the optimal edge location by looking at a truncated version of the end user’s IP address added into the DNS request. Today, Google Public DNS and Open DNS are two providers that include this truncated IP address (specifically, the first three octets) of the end user in the DNS request. For more information about how EDNS-Client-Subnet works, see A Faster Internet.
You don’t need to do anything to enable this feature; Amazon CloudFront will automatically route all requests using Google Public DNS and Open DNS to the edge location that provides the best possible performance.