You're migrating an existing application to the AWS cloud. The application will be primarily using EC2 instances. This application needs to be built with the highest availability architecture available. The application currently relies on hardcoded hostnames for intercommunication between the three tiers. You've migrated the application and configured the multi-tiers using the internal Elastic Load Balancer for serving the traffic. The load balancer hostname is . The current hard-coded hostname in your application used to communicate between your multi-tier application is . What is the best method for architecting this setup to have as much high availability as possible? Choose the correct answer from the below options:
A. Create an environment variable passed to the EC2 instances using user-data with the ELB hostname, .
B. Create a private resource record set using Route 53 with a hostname of and an alias record to .
C. Create a public resource record set using Route 53 with a hostname of and an alias record to .
D. Add a cname record to the existing on-premise DNS server with a value of . Create a public resource record set using Route 53 with a hostname of and an alias record to .
