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AWS GovCloud (US)
User Guide

Setting Up Amazon Route 53 Zone Apex Support with an AWS GovCloud (US) Elastic Load Balancing Load Balancer

Amazon Route 53 is a highly available and scalable Domain Name System (DNS) web service. It is designed to provide an extremely reliable and cost effective way to route end users to Internet applications by translating human readable names like www.example-company.com into numeric IP addresses like 192.168.0.1 that computers use to connect to each other.

Amazon Route 53's DNS implementation connects user requests to infrastructure running inside (and outside) of Amazon Web Services (AWS). For example, if you have multiple web servers running on Amazon Elastic Compute Cloud (Amazon EC2) instances behind an Elastic Load Balancing load balancer, Amazon Route 53 will route all traffic addressed to your website (e.g. www.example.com) to the load balancer DNS name (e.g. elb1234.elb.amazonaws.com).

Additionally, Amazon Route 53 supports the alias resource record set, which lets you map your zone apex (e.g. example.com) DNS name to your load balancer DNS name. IP addresses associated with Elastic Load Balancing can change at any time due to scaling or software updates. Amazon Route 53 responds to each request for an alias resource record set with one IP address for the load balancer. If a load balancer has more than one IP address, Elastic Load Balancing selects one of the IP addresses in a round-robin fashion and returns it to Amazon Route 53; Amazon Route 53 then responds to the request with that IP address.

Alias resource record sets are virtual records that work like CNAME records. But they differ from CNAME records in that they are not visible to resolvers. Resolvers only see the A record and the resulting IP address of the target record. As such, unlike CNAME records, alias resource record sets are available to configure a zone apex (also known as a root domain or naked domain) in a dynamic environment.

This section provides a solution for Amazon Route 53 zone apex alias support by setting up an Amazon CloudFront distribution between Amazon Route 53 and an AWS GovCloud (US) Elastic Load Balancing load balancer. The solution demonstrates how to configure Amazon Route 53 with a zone apex alias resource record set that maps to a CloudFront web distribution DNS name. The CloudFront distribution in turn points to the AWS GovCloud (US) load balancer DNS name as a custom origin.

An additional benefit of this approach is that CloudFront can help improve the performance of your website, including both static and dynamic content. For more information about CloudFront, see the CloudFront documentation.

The following figure shows the various AWS services used to demonstrate this solution: