AWS Certified Solutions Architect – Associate (SAA-C03) — Question 725

A company’s application is deployed on Amazon EC2 instances and uses AWS Lambda functions for an event-driven architecture. The company uses nonproduction development environments in a different AWS account to test new features before the company deploys the features to production.

The production instances show constant usage because of customers in different time zones. The company uses nonproduction instances only during business hours on weekdays. The company does not use the nonproduction instances on the weekends. The company wants to optimize the costs to run its application on AWS.

Which solution will meet these requirements MOST cost-effectively?

Answer options

• A. Use On-Demand Instances for the production instances. Use Dedicated Hosts for the nonproduction instances on weekends only.
• B. Use Reserved Instances for the production instances and the nonproduction instances. Shut down the nonproduction instances when not in use.
• C. Use Compute Savings Plans for the production instances. Use On-Demand Instances for the nonproduction instances. Shut down the nonproduction instances when not in use.
• D. Use Dedicated Hosts for the production instances. Use EC2 Instance Savings Plans for the nonproduction instances.

Correct answer: C

Explanation

Compute Savings Plans are the most cost-effective choice for the production environment because they offer significant discounts on steady-state EC2 and AWS Lambda usage across accounts. For the nonproduction environments, which are shut down during nights and weekends, On-Demand Instances are ideal because you only pay for the active hours, avoiding the waste of a long-term commitment. Dedicated Hosts and Reserved Instances would introduce unnecessary overhead and costs for resources that remain idle for a large portion of the week.