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.

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.

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.

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.