What is the MOST cost-effective action that should be taken to avoid downtime?

A company is running Amazon RDS for MySQL for its workloads. There is downtime when AWS operating system patches are applied during the Amazon RDS-specified maintenance window.

What is the MOST cost-effective action that should be taken to avoid downtime?
A . Migrate the workloads from Amazon RDS for MySQL to Amazon DynamoDB
B . Enable cross-Region read replicas and direct read traffic to then when Amazon RDS is down
C . Enable a read replicas and direct read traffic to it when Amazon RDS is down
D . Enable an Amazon RDS for MySQL Multi-AZ configuration

View Answer

Answer: D

Explanation:

https://aws.amazon.com/premiumsupport/knowledge-center/rds-required-maintenance/

To minimize downtime, modify the Amazon RDS DB instance to a Multi-AZ deployment. For Multi-AZ deployments, OS maintenance is applied to the secondary instance first, then the instance fails over, and then the primary instance is updated. The downtime is during failover. For more information, see Maintenance for Multi-AZ Deployments. https://aws.amazon.com/rds/faqs/ The availability benefits of Multi-AZ also extend to planned maintenance. For example, with automated backups, I/O activity is no longer suspended on your primary during your preferred backup window, since backups are taken from the standby. In the case of patching or DB instance class scaling, these operations occur first on the standby, prior to automatic fail over. As a result, your availability impact is limited to the time required for automatic failover to complete.