AWS Certified Solutions Architect – Associate (SAA-C03) — Question 265

A company runs an application on Amazon EC2 instances. The company needs to implement a disaster recovery (DR) solution for the application. The DR solution needs to have a recovery time objective (RTO) of less than 4 hours. The DR solution also needs to use the fewest possible AWS resources during normal operations.

Which solution will meet these requirements in the MOST operationally efficient way?

Answer options

• A. Create Amazon Machine Images (AMIs) to back up the EC2 instances. Copy the AMIs to a secondary AWS Region. Automate infrastructure deployment in the secondary Region by using AWS Lambda and custom scripts.
• B. Create Amazon Machine Images (AMIs) to back up the EC2 instances. Copy the AMIs to a secondary AWS Region. Automate infrastructure deployment in the secondary Region by using AWS CloudFormation.
• C. Launch EC2 instances in a secondary AWS Region. Keep the EC2 instances in the secondary Region active at all times.
• D. Launch EC2 instances in a secondary Availability Zone. Keep the EC2 instances in the secondary Availability Zone active at all times.

Correct answer: B

Explanation

Using a Backup and Restore strategy with Amazon Machine Images (AMIs) copied to a secondary AWS Region minimizes resource consumption and cost during normal operations, easily meeting the 4-hour RTO requirement. Automating the recovery environment using AWS CloudFormation is more operationally efficient and less error-prone than writing and maintaining custom AWS Lambda scripts. Options C and D keep EC2 instances running continuously, which does not meet the requirement of using the fewest possible AWS resources.