AWS Certified Cloud Practitioner — Question 985

A company needs an Amazon EC2 instance for a rightsized database server that must run constantly for 1 year.
Which EC2 instance purchasing option will meet these requirements MOST cost-effectively?

Answer options

• A. Standard Reserved Instance
• B. Convertible Reserved Instance
• C. On-Demand Instance
• D. Spot Instance

Correct answer: A

Explanation

Standard Reserved Instances offer the most significant discount (up to 72%) for steady-state workloads with a 1-year commit, making them the most cost-effective choice for a rightsized database. Convertible Reserved Instances offer lower discounts and are unnecessary here since the instance size is already optimized, while On-Demand Instances are too expensive for continuous workloads. Spot Instances are not suitable because they can be interrupted, which violates the requirement for the database to run constantly.