AWS Certified SysOps Administrator – Associate — Question 328

A company has a stateless application that is hosted on a fleet of 10 Amazon EC2 On-Demand Instances in an Auto Scaling group. A minimum of 6 instances are needed to meet service requirements.

Which action will maintain uptime for the application MOST cost-effectively?

Answer options

• A. Use a Spot Fleet with an On-Demand capacity of 6 instances.
• B. Update the Auto Scaling group with a minimum of 6 On-Demand Instances and a maximum of 10 On-Demand Instances.
• C. Update the Auto Scaling group with a minimum of 1 On-Demand Instance and a maximum of 6 On-Demand Instances.
• D. Use a Spot Fleet with a target capacity of 6 instances.

Correct answer: A

Explanation

To guarantee the minimum service requirement of 6 instances for baseline uptime, the system must use at least 6 reliable, non-interruptible On-Demand Instances. Utilizing Spot Instances for any capacity requirements beyond this baseline provides the most cost-effective scaling solution for a stateless application. Other options either fail to guarantee the minimum required instances during a Spot interruption or are less cost-effective by relying solely on On-Demand Instances.