AWS Certified Solutions Architect – Professional — Question 609

A company plans to deploy a new private intranet service on Amazon EC2 instances inside a VPC. An AWS Site-to-Site VPN connects the VPC to the company's on-premises network. The new service must communicate with existing on-premises services. The on-premises services are accessible through the use of hostnames that reside in the company.example DNS zone. This DNS zone is wholly hosted on premises and is available only on the company's private network.
A solutions architect must ensure that the new service can resolve hostnames on the company example domain to integrate with existing services.
Which solution meets these requirements?

Answer options

• A. Create an empty private zone in Amazon Route 53 for company example. Add an additional NS record to the company's on-premises company.example zone that points to the authoritative name servers for the new private zone in Route 53.
• B. Turn on DNS hostnames for the VPC. Configure a new outbound endpoint with Amazon Route 53 Resolver. Create a Resolver rule to forward requests for company.example to the on-premises name servers.
• C. Turn on DNS hostnames for the VPC. Configure a new inbound resolver endpoint with Amazon Route 53 Resolver. Configure the on-premises DNS server to forward requests for company.example to the new resolver.
• D. Use AWS Systems Manager to configure a run document that will install a hosts file that contains any required hostnames. Use an Amazon EventBridge (Amazon CloudWatch Events) rule to run the document when an instance is entering the running state.

Correct answer: B

Explanation

To resolve DNS queries for an on-premises domain from within an AWS VPC, Route 53 Resolver requires an outbound endpoint coupled with a forwarding rule for the target domain (company.example) pointing to the on-premises DNS servers. Inbound endpoints are used for the opposite flow (resolving AWS DNS from on-premises), making Option C incorrect. Managing a static hosts file via Systems Manager is not scalable and does not leverage native AWS DNS resolution capabilities.