AWS Certified Solutions Architect – Associate (SAA-C03) — Question 503

A company has Amazon EC2 instances that run nightly batch jobs to process data. The EC2 instances run in an Auto Scaling group that uses On-Demand billing. If a job fails on one instance, another instance will reprocess the job. The batch jobs run between 12:00 AM and 06:00 AM local time every day.

Which solution will provide EC2 instances to meet these requirements MOST cost-effectively?

Answer options

• A. Purchase a 1-year Savings Plan for Amazon EC2 that covers the instance family of the Auto Scaling group that the batch job uses.
• B. Purchase a 1-year Reserved Instance for the specific instance type and operating system of the instances in the Auto Scaling group that the batch job uses.
• C. Create a new launch template for the Auto Scaling group. Set the instances to Spot Instances. Set a policy to scale out based on CPU usage.
• D. Create a new launch template for the Auto Scaling group. Increase the instance size. Set a policy to scale out based on CPU usage.

Correct answer: C

Explanation

Spot Instances provide the highest discount (up to 90% off On-Demand rates) and are ideal for workloads that are fault-tolerant and run for short periods, such as this 6-hour nightly batch job. Reserved Instances and Savings Plans require a continuous commitment and are less cost-effective for workloads that only run a fraction of the day. Increasing the instance size with On-Demand billing would increase costs rather than minimize them.