AWS Certified Cloud Practitioner — Question 577

A company runs Amazon EC2 instances in a research lab. The instances run for 3 hours each week and cannot be interrupted.

What is the MOST cost-effective instance purchasing option to meet these requirements?

Answer options

• A. Compute Savings Plan
• B. On-Demand Instances
• C. Convertible Reserved Instances
• D. Spot Instances

Correct answer: B

Explanation

On-Demand Instances are the most cost-effective choice because they charge by the second with no long-term commitment, making them ideal for low-utilization workloads that run for only 3 hours a week. Spot Instances are not suitable because they can be interrupted, while Savings Plans and Reserved Instances require committed usage over 1 or 3 years, which would result in paying for idle time.