Which solution will meet these requirements MOST cost-effectively?
Create a cross-Region read replica and promote the read replica to the primary instance.
Use AWS Database Migration Service (AWS DMS) to create RDS cross-Region replication.
Use cross-Region replication every 24 hours to copy native backups to an Amazon S3 bucket.
Copy automatic snapshots to another Region every 24 hours.
Explanations:
Cross-Region read replicas are used for scaling and read-heavy workloads, but they are not suitable for a disaster recovery solution with a 24-hour RPO and RTO. The replica would need to be promoted to a primary instance, and this process is typically more time-consuming than required for an RTO of 24 hours.
AWS Database Migration Service (DMS) is primarily used for migrating databases, not for continuous replication to support disaster recovery. DMS is not a cost-effective or optimal solution for meeting the RPO and RTO requirements for Amazon RDS SQL Server.
Copying native backups to an S3 bucket every 24 hours does not provide the necessary continuous replication to meet the 24-hour RPO. There is also no automatic failover mechanism, which is necessary for meeting the RTO. This solution may also involve more manual management.
Copying automatic snapshots to another Region every 24 hours is a simple and cost-effective disaster recovery solution. Snapshots can be used to restore the database in a different Region. With an RPO of 24 hours, this approach meets the requirement of taking a snapshot every 24 hours, providing a simple backup solution.
I chart that the answer is:
Copy automatic snapshots to another Region every 24 hours.