Amazon Exam ANS-C01 Topic 4 Question 57 Discussion

The correct solution is to use a Route 53 private hosted zone and a Route 53 Resolver inbound endpoint. A private hosted zone allows you to use private domain names for your internal AWS resources without exposing them to the internet. A Route 53 Resolver inbound endpoint enables DNS queries from your on-premises network to be forwarded to your VPC. By configuring conditional forwarding on your on-premises DNS resolvers, you can ensure that only the queries for the AWS reserved domain name are sent to the inbound endpoint. In the private hosted zone, you can create primary and failover records that point to the IP addresses of the EC2 instances. These records will automatically switch to the failover instance if the primary instance becomes unhealthy. You can use CloudWatch metrics and alarms to monitor the application's health and trigger the health check for the primary endpoint.

The other options are not correct because they either expose the application to the internet or use a public hosted zone, which is not suitable for internal applications. Option A assigns public IP addresses to the EC2 instances, which makes them accessible from the internet. Option B uses a public hosted zone, which requires the EC2 instances to have public IP addresses or elastic IP addresses. Option D does not set up a health check on the alarm for the primary endpoint, which is required for the failover mechanism to work.