AWS Certified Solutions Architect – Associate (SAA-C03) — Question 811

A company hosts its application in the AWS Cloud. The application runs on Amazon EC2 instances in an Auto Scaling group behind an Elastic Load Balancing (ELB) load balancer. The application connects to an Amazon DynamoDB table.

For disaster recovery (DR) purposes, the company wants to ensure that the application is available from another AWS Region with minimal downtime.

Which solution will meet these requirements with the LEAST downtime?

Answer options

• A. Create an Auto Scaling group and an ELB in the DR Region. Configure the DynamoDB table as a global table. Configure DNS failover to point to the new DR Region's ELB.
• B. Create an AWS CloudFormation template to create EC2 instances, ELBs, and DynamoDB tables to be launched when necessary. Configure DNS failover to point to the new DR Region's ELB.
• C. Create an AWS CloudFormation template to create EC2 instances and an ELB to be launched when necessary. Configure the DynamoDB table as a global table. Configure DNS failover to point to the new DR Region's ELB.
• D. Create an Auto Scaling group and an ELB in the DR Region. Configure the DynamoDB table as a global table. Create an Amazon CloudWatch alarm with an evaluation period of 10 minutes to invoke an AWS Lambda function that updates Amazon Route 53 to point to the DR Region's ELB.

Correct answer: A

Explanation

Option A provides the lowest downtime because the Auto Scaling group and ELB are already running in the DR Region, and DynamoDB global tables ensure real-time data replication, allowing Route 53 DNS failover to redirect traffic instantly. Options B and C require deploying infrastructure from AWS CloudFormation templates during a disaster, which introduces significant recovery time. Option D introduces an intentional and unnecessary 10-minute delay due to the CloudWatch alarm evaluation period, which does not meet the requirement for minimal downtime.