AWS Certified Solutions Architect – Associate (SAA-C03) — Question 959

A company's production environment consists of Amazon EC2 On-Demand Instances that run constantly between Monday and Saturday. The instances must run for only 12 hours on Sunday and cannot tolerate interruptions. The company wants to cost-optimize the production environment.

Which solution will meet these requirements MOST cost-effectively?

Answer options

• A. Purchase Scheduled Reserved Instances for the EC2 instances that run for only 12 hours on Sunday. Purchase Standard Reserved Instances for the EC2 instances that run constantly between Monday and Saturday.
• B. Purchase Convertible Reserved Instances for the EC2 instances that run for only 12 hours on Sunday. Purchase Standard Reserved Instances for the EC2 instances that run constantly between Monday and Saturday.
• C. Use Spot Instances for the EC2 instances that run for only 12 hours on Sunday. Purchase Standard Reserved Instances for the EC2 instances that run constantly between Monday and Saturday.
• D. Use Spot Instances for the EC2 instances that run for only 12 hours on Sunday. Purchase Convertible Reserved Instances for the EC2 instances that run constantly between Monday and Saturday.

Correct answer: A

Explanation

Standard Reserved Instances provide the highest discount rate for steady-state workloads running continuously from Monday to Saturday. Because the Sunday workload cannot tolerate interruptions, Spot Instances are ruled out. Scheduled Reserved Instances are the most cost-effective option for predictable, recurring workloads that only run during specific windows, such as 12 hours every Sunday.