AWS Certified Solutions Architect – Associate (SAA-C03) — Question 310

A company’s application runs on Amazon EC2 instances behind an Application Load Balancer (ALB). The instances run in an Amazon EC2 Auto Scaling group across multiple Availability Zones. On the first day of every month at midnight, the application becomes much slower when the month-end financial calculation batch runs. This causes the CPU utilization of the EC2 instances to immediately peak to 100%, which disrupts the application.

What should a solutions architect recommend to ensure the application is able to handle the workload and avoid downtime?

Answer options

• A. Configure an Amazon CloudFront distribution in front of the ALB.
• B. Configure an EC2 Auto Scaling simple scaling policy based on CPU utilization.
• C. Configure an EC2 Auto Scaling scheduled scaling policy based on the monthly schedule.
• D. Configure Amazon ElastiCache to remove some of the workload from the EC2 instances.

Correct answer: C

Explanation

Because the CPU spike occurs at a highly predictable, recurring time, a scheduled scaling policy is the ideal solution to scale out the EC2 instances proactively before the batch job starts. Reactive scaling policies like simple scaling based on CPU would respond too late to prevent the initial performance degradation. Solutions like CloudFront and ElastiCache do not address the CPU-intensive nature of the monthly batch calculations.