AWS Certified Cloud Practitioner — Question 56

A user is comparing purchase options for an application that runs on Amazon EC2 and Amazon RDS. The application cannot sustain any interruption. The application experiences a predictable amount of usage, including some seasonal spikes that last only a few weeks at a time. It is not possible to modify the application.
Which purchase option meets these requirements MOST cost-effectively?

Answer options

• A. Review the AWS Marketplace and buy Partial Upfront Reserved Instances to cover the predicted and seasonal load.
• B. Buy Reserved Instances for the predicted amount of usage throughout the year. Allow any seasonal usage to run on Spot Instances.
• C. Buy Reserved Instances for the predicted amount of usage throughout the year. Allow any seasonal usage to run at an On-Demand rate.
• D. Buy Reserved Instances to cover all potential usage that results from the seasonal usage.

Correct answer: C

Explanation

Option C is correct because it allows for predictable usage to be covered by Reserved Instances while using On-Demand pricing for seasonal spikes, ensuring no interruptions. Option A is less cost-effective as Partial Upfront Reserved Instances may not cover all needs. Option B risks interruptions during seasonal spikes due to reliance on Spot Instances. Option D is unnecessarily expensive as it requires covering all potential seasonal usage with Reserved Instances.