wording of an answer not clear

[wail-el-edghiri]

Hello team,

I hope you are doing well 🙂

I’m going through the practice exam 1 on review mode for the devops certification.

I came across the following question:

A popular e-commerce website that has customers across the globe is hosted in the us-east-1 AWS region with a backup site in the us-west-1 region. Due to an unexpected regional outage in the us-east-1 region, the company initiated its disaster recovery plan and turned on the backup site. However, the company discovered that the actual failover still entails several hours of manual effort to prepare and switch over the database. The company also noticed the database missing up to three hours of data transactions during the regional outage.

Which of the following solutions should the DevOps engineer implement to improve the RTO and RPO of the website for the cross-region failover?

One of the proposed answers is this:

Use Step Functions with 2 Lambda functions that call the RDS API to create a snapshot of the database, create a cross-region snapshot copy, and restore the database instance from a snapshot in the backup region. Use Amazon EventBridge to trigger the function to take a database snapshot every hour. Set up an SNS topic that will receive published messages from AWS Health API, RDS availability, and other events that will trigger the Lambda function to create a cross-region snapshot copy. During failover, configure the Lambda function to restore the database from a snapshot in the backup region.

here we are saying that:

we use a step function with 2 lambdas to perform snapshot, copy and restore the database in the other region. But after that i don’t understand the wording:

Use Amazon EventBridge to trigger the function to take a database snapshot every hour. Set up an SNS topic that will receive published messages from AWS Health API, RDS availability, and other events that will trigger the Lambda function to create a cross-region snapshot copy.

During failover, configure the Lambda function to restore the database from a snapshot in the backup region.

what’s the function that will be triggered by eventbridge and what’s the function that will be triggered by health API and how the step function function is used?

As i understand it, we have 2 lambdas one that’s doing snapshot and cross region copy and another lambda which is doing the restore. Ideally, one should be in each region. Specially the second one, because if we lose the primary region as stated in the scenario, we will not be able to use it from the primary region. if it’s that the case i understood the role of each lambda. But i don’t understand the purpose of using step function since i see the step function as being a workflow that’s being run totally and not each lambda alone.

So what’s the purpose of using step functions?

I noticed same thing with another proposed solution

Use an ECS cluster to host a custom python script that calls the RDS API to create a snapshot of the database, create a cross-region snapshot copy, and restore the database instance from a snapshot in the backup region. Create a scheduled rule using Amazon EventBridge that triggers “the Lambda” function to snapshot a database instance every hour. Set up an SNS topic that will receive published messages about AWS-initiated RDS events from Trusted Advisor that will trigger the function to create a cross-region snapshot copy. During failover, restore the database from a snapshot in the backup region.

What’s ” the lambda function” here?

I’m confused about it, i don’t understand what’s the proposed solutions?
could you please clarify? I may have missed something or mixed up everything haha.

Thanks in advance for your response 🙂

[Irene-TutorialsDojo]

Hello wail-el-edghiri,

Thank you for taking the time to raise this and for the detailed explanation of your concern — you were absolutely right to question the original wording.

We’ve reviewed the item and updated the question, Option 2, and the explanation to clearly define the roles of each AWS service involved and remove any ambiguity. The revised version now explicitly states:

• Which Lambda function is triggered by Amazon EventBridge (scheduled snapshot creation and cross-Region snapshot copy in the primary Region),

• Which Lambda function is triggered by AWS Health and Amazon RDS events via Amazon SNS (database restore in the backup Region during failover),

• And how AWS Step Functions are used strictly for orchestration, providing sequencing, retries, and error handling across the workflow rather than acting as a trigger.

These updates align with the latest AWS documentation for Amazon RDS cross-Region snapshot copy and restore workflows, and better reflect how snapshot-based disaster recovery improves RTO and RPO compared to a manual recovery process.

Your understanding was correct, especially regarding the need for the restore logic to run in the backup Region and the role of Step Functions as an orchestration layer. We appreciate you pointing this out, as it helped us improve the clarity and accuracy of the question for all learners.

If you have any further questions or need additional clarification, feel free to reach out anytime 🙂

Cheers,

Irene @ Tutorials Dojo