AWS Certified Solutions Architect – Professional (SAP-C02) — Question 374

A company needs to implement a disaster recovery (DR) plan for a web application. The application runs in a single AWS Region.

The application uses microservices that run in containers. The containers are hosted on AWS Fargate in Amazon Elastic Container Service (Amazon ECS). The application has an Amazon RDS for MySQL DB instance as its data layer and uses Amazon Route 53 for DNS resolution. An Amazon CloudWatch alarm invokes an Amazon EventBridge rule if the application experiences a failure.

A solutions architect must design a DR solution to provide application recovery to a separate Region. The solution must minimize the time that is necessary to recover from a failure.

Which solution will meet these requirements?

Answer options

• A. Setup a second ECS cluster and ECS service on Fargate in the separate Region. Create an AWS Lambda function to perform the following actions: take a snapshot of the RDS DB instance, copy the snapshot to the separate Region, create a new RDS DB instance from the snapshot, and update Route 53 to route traffic to the second ECS cluster. Update the EventBridge rule to add a target that will invoke the Lambda function.
• B. Create an AWS Lambda function that creates a second ECS cluster and ECS service in the separate Region. Configure the Lambda function to perform the following actions: take a snapshot of the RDS DB instance, copy the snapshot to the separate Region, create a new RDS DB instance from the snapshot, and update Route 53 to route traffic to the second ECS cluster. Update the EventBridge rule to add a target that will invoke the Lambda function.
• C. Setup a second ECS cluster and ECS service on Fargate in the separate Region. Create a cross-Region read replica of the RDS DB instance in the separate Region. Create an AWS Lambda function to promote the read replica to the primary database. Configure the Lambda function to update Route 53 to route traffic to the second ECS cluster. Update the EventBridge rule to add a target that will invoke the Lambda function.
• D. Setup a second ECS cluster and ECS service on Fargate in the separate Region. Take a snapshot of the RDS DB instance. Convert the snapshot to an Amazon DynamoDB global table. Create an AWS Lambda function to update Route 53 to route traffic to the second ECS cluster. Update the EventBridge rule to add a target that will invoke the Lambda function.

Correct answer: C

Explanation

Option C is correct because pre-provisioning the ECS resources in the recovery Region and maintaining a cross-Region RDS read replica provides the lowest Recovery Time Objective (RTO). Promoting a read replica to a primary database is significantly faster during a disaster than restoring a database from a snapshot, which rules out Options A and B. Option D is incorrect because converting a relational MySQL database to a DynamoDB global table on the fly is highly impractical and would break application compatibility.