You are moving an existing traditional system to AWS. During migration, you discover that the master server is the single point of failure. You also discover that the server stores its state in the local MySQL database. To minimize downtime, you select RDS to replace the local database and configure the master to use it. What steps would best allow you to create a self-healing architecture?

Answer options:

A.Migrate the local database into the Multi-AZ database. Amazon RDS detects and automatically recovers from the most common failure scenarios for Multi-AZ deployments. Configure the master node in an Auto Scaling group.
B.Migrate the local database into the Multi-AZ database. Place the master node into a Cross Zone ELB with a minimum of one and a maximum of one with health checks.
C.Replicate the local database into an RDS database with a Read Replica. Place the master node into a Cross Zone ELB with a minimum of one and a maximum of one with health checks.
D.Replicate the local database into an RDS database with a Read Replica. Configure the master node in an Auto Scaling group.

Answer - A
Option A is CORRECT because, for the database, Multi-AZ architecture provides high availability and can meet the RTO and RPO requirements in case of failures since it uses synchronous replication and maintains standby instance gets promoted to primary. Auto Scaling group can achieve the high availability for the master server.
Option B is incorrect because ELB cannot ensure the minimum or the maximum number of instances running.
Option C is incorrect because ELB cannot ensure the minimum or the maximum number of instances running.
Option D is incorrect because the Read Replica cannot achieve the self-healing requirements. Multi-AZ should be used.
More information on Multi-AZ RDS architecture:
Multi-AZ is used for highly available architecture. If a failover happens, the secondary DB, which is a synchronous replica, will have the data, and it’s just the CNAME that changes. For Read replica, it’s primarily used for distributing workloads.
For more information on Multi-AZ RDS, please refer to the below link-
https://aws.amazon.com/rds/details/multi-az/