AWS Certified Advanced Networking – Specialty (ANS-C01) — Question 169

A company is planning to migrate an internal application to the AWS Cloud. The application will run on Amazon EC2 instances in one VPC. Users will access the application from the company's on-premises data center through AWS VPN or AWS Direct Connect. Users will use private domain names for the application endpoint from a domain name that is reserved explicitly for use in the AWS Cloud.

Each EC2 instance must have automatic failover to another EC2 instance in the same AWS account and the same VPC. A network engineer must design a DNS solution that will not expose the application to the internet.

Which solution will meet these requirements?

Answer options

• A. Assign public IP addresses to the EC2 instances. Create an Amazon Route 53 private hosted zone for the AWS reserved domain name. Associate the private hosted zone with the VPC. Create a Route 53 Resolver outbound endpoint. Configure conditional forwarding in the on-premises DNS resolvers to forward all DNS queries for the AWS domain to the outbound endpoint IP address for Route 53 Resolver. In the private hosted zone, configure primary and failover records that point to the public IP addresses of the EC2 instances. Create an Amazon CloudWatch metric and alarm to monitor the application's health. Set up a health check on the alarm for the primary application endpoint.
• B. Place the EC2 instances in private subnets. Create an Amazon Route 53 public hosted zone for the AWS reserved domain name. Associate the public hosted zone with the VPC. Create a Route 53 Resolver inbound endpoint. Configure conditional forwarding in the on-premises DNS resolvers to forward all DNS queries for the AWS domain to the inbound endpoint IP address for Route 53 Resolver. In the public hosted zone, configure primary and failover records that point to the IP addresses of the EC2 instances. Create an Amazon CloudWatch metric and alarm to monitor the application's health. Set up a health check on the alarm for the primary application endpoint.
• C. Place the EC2 instances in private subnets. Create an Amazon Route 53 private hosted zone for the AWS reserved domain name. Associate the private hosted zone with the VPCreate a Route 53 Resolver inbound endpoint. Configure conditional forwarding in the on-premises DNS resolvers to forward all DNS queries for the AWS domain to the inbound endpoint IP address for Route 53 Resolver. In the private hosted zone, configure primary and failover records that point to the IP addresses of the EC2 instances. Create an Amazon CloudWatch metric and alarm to monitor the application's health. Set up a health check on the alarm for the primary application endpoint.
• D. Place the EC2 instances in private subnets. Create an Amazon Route 53 private hosted zone for the AWS reserved domain name. Associate the private hosted zone with the VPC. Create a Route 53 Resolver inbound endpoint. Configure conditional forwarding in the on-premises DNS resolvers to forward all DNS queries for the AWS domain to the inbound endpoint IP address for Route 53 Resolver. In the private hosted zone, configure primary and failover records that point to the IP addresses of the EC2 instances. Set up Route 53 health checks on the private IP addresses of the EC2 instances.

Correct answer: C

Explanation

The correct answer is C because it places the EC2 instances in private subnets and uses a private hosted zone, ensuring that the application is not exposed to the internet. Option A is incorrect as it assigns public IP addresses, which contradicts the requirement. Option B is wrong because it suggests a public hosted zone, which would expose the application. Option D, while using a private hosted zone, incorrectly suggests setting up health checks on private IPs instead of failing over correctly, which makes it less suitable.