Set up DNS resolution for hybrid networks in a multi-account AWS environment

Created by Amir Durrani

Environment: Production

Technologies: Infrastructure; Networking

AWS services: AWS RAM; Amazon Route 53; AWS Control Tower

Summary

This pattern describes how you can use on-premises Domain Name System (DNS) services with Amazon Route 53 Resolver rules and outbound Resolver endpoints for name resolution.

DNS is fundamental to establishing and maintaining communications across network environments. If you have a hybrid network connectivity environment, you can share critical network services such as DNS and Active Directory without the operational burden of managing a distributed environment across accounts and virtual private clouds (VPCs). This approach helps you build and support applications that span a large number of accounts. For example, if you have hundreds or thousands of multi-Region accounts with hybrid connectivity requirements, you can share DNS services securely and efficiently across all connected environments within your AWS organization.

DNS is critical to IP networking among all tiers (web, application, and database) of an application. It is best practice to give only the team of DNS experts full access to configure, operate, and support this resource. In a hybrid connectivity environment, you can continue to use your on-premises DNS for name resolution requests originating from resources that reside in different accounts, by using conditional forwarding.

This pattern covers hybrid DNS resolution in an AWS multi-account environment. For single accounts, see the pattern Set up DNS resolution for hybrid networks in a single-account AWS environment.

Prerequisites and limitations

Prerequisites 

• An AWS multi-account environment that is based on best practices and built by using AWS Control Tower. The diagram in the next section shows the typical architecture of such an environment.

• Scalable routing infrastructure between the accounts and VPCs by using AWS Transit Gateway.

• Outbound Resolver endpoints and Resolver rules by using Amazon Route 53.

• Resource shares for outbound Resolver rules by using AWS Resource Access Manager (AWS RAM).

Architecture

AWS multi-account architecture

Target technology stack  

• An existing on-premises DNS infrastructure for outbound name resolution across a large number of AWS principals 

• Route 53 Resolver rule and outbound Resolver endpoints

• AWS RAM for sharing Route 53 Resolver rules with other AWS principals within and outside the AWS organization

Target architecture 

The following diagram depicts the steps for configuring the end-to-end hybrid DNS resolution. AWS RAM is used to share the Route 53 Resolver rules and Resolver endpoints, which are configured and managed from the central Shared Services account. Route 53 Resolver endpoints are configured for each Availability Zone to receive the outbound name resolution requests for the resources that reside in the on-premises data center, and to then forward these requests to the on-premises DNS resolvers. The on-premises DNS resolvers send the name resolution responses to the outbound endpoints, which then forward the responses to the VPC resolver. These steps establish end-to-end communication by using hostnames instead of IP addresses.

The following diagram shows the architecture in more detail.

Automation and scale

You can configure and share Route 53 Resolver rules through AWS RAM by using AWS CloudFormation templates. 

Tools

AWS services

• AWS Control Tower helps you set up and govern an AWS multi-account environment, following prescriptive best practices.

• AWS Resource Access Manager (AWS RAM) helps you securely share your resources across AWS accounts to reduce operational overhead and provide visibility and auditability.

• Amazon Route 53 is a highly available and scalable DNS web service.

Additional tools

• nslookup and dig are utilities for querying DNS records.

Epics

Configure the Resolver endpoints and rules

Task	Description	Skills required
Configure Route 53 outbound Resolver endpoints and rules.	Sign in to the AWS Management Console for the AWS account that you want to configure and share the Route 53 outbound Resolver rule from. Open the Route 53 console at https://console.aws.amazon.com/route53/. On the navigation bar, choose the Region where you want to configure the Resolver endpoint. In the navigation pane, choose Outbound endpoints, and then choose Configure endpoints. Provide general settings, IP addresses, and optional tag information, and then choose Next. Create one or more rules to specify the domain names of the DNS queries that you want to forward to your network, and then choose Save. For more information, see Forwarding outbound DNS queries to your network in the Route 53 documentation.	General AWS
Create and share Route 53 outbound Resolver rules with AWS principals.	Open the AWS RAM console at https://console.aws.amazon.com/ram/. In the navigation pane, choose Resource shares, and then choose Create resource share. Provide a share name. For resource type, choose Resolver Rules. Choose the Resolver rule that you want to share, provide optional tag key and value information, and then choose Next. Choose the principals that you want to share the Resolver rule resource with. Principals can be internal or external to your AWS organization. For example, you can choose your AWS organization, a specific organizational unit (OU) within the organization, or a specific account. Review and create the resource share. After the resource is created and shared, it appears in the Shared with me section of the navigation pane for the principals it is shared with. Associate the VPCs in the (principal) account with the Resolver rule that has been shared by the shared services or networking account. For more information, see Sharing your AWS resources in the AWS RAM documentation.	General AWS
Test the outbound DNS name resolution.	Test the name resolution by using the nslookup or dig utility on instances in a VPC in an account that you have shared the Resolver rule with. The query should resolve to the IP address of a resource that resides within your on-premises data center.	General AWS

Related resources

• Resolving on-prem DNS in hybrid environments (video)

• Forwarding outbound DNS queries to your network (Route 53 documentation)

• Sharing your AWS resources (AWS RAM documentation)