AWS Certified Solutions Architect – Associate (SAA-C02) — Question 268

A company runs an application on an Amazon EC2 instance backed by Amazon Elastic Block Store (Amazon EBS). The instance needs to be available for 12 hours daily. The company wants to save costs by making the instance unavailable outside the window required for the application. However, the contents of the instance's memory must be preserved whenever the instance is unavailable.
What should a solutions architect do to meet this requirement?

Answer options

• A. Stop the instance outside the application's availability window. Start up the instance again when required.
• B. Hibernate the instance outside the application's availability window. Start up the instance again when required.
• C. Use Auto Scaling to scale down the instance outside the application's availability window. Scale up the instance when required.
• D. Terminate the instance outside the application's availability window. Launch the instance by using a preconfigured Amazon Machine Image (AMI) when required.

Correct answer: B

Explanation

Hibernating an Amazon EC2 instance saves the contents of its RAM to the EBS root volume, allowing the instance to resume from its exact state when restarted, which fulfills the memory preservation requirement. Stopping the instance clears the RAM, while terminating the instance deletes the instance entirely. Auto Scaling would launch new instances from scratch, losing any in-memory state.