AWS Certified Solutions Architect – Associate (SAA-C03) — Question 830

A company’s application is running on Amazon EC2 instances within an Auto Scaling group behind an Elastic Load Balancing (ELB) load balancer. Based on the application's history, the company anticipates a spike in traffic during a holiday each year. A solutions architect must design a strategy to ensure that the Auto Scaling group proactively increases capacity to minimize any performance impact on application users.

Which solution will meet these requirements?

Answer options

• A. Create an Amazon CloudWatch alarm to scale up the EC2 instances when CPU utilization exceeds 90%.
• B. Create a recurring scheduled action to scale up the Auto Scaling group before the expected period of peak demand.
• C. Increase the minimum and maximum number of EC2 instances in the Auto Scaling group during the peak demand period.
• D. Configure an Amazon Simple Notification Service (Amazon SNS) notification to send alerts when there are autoscaling:EC2_INSTANCE_LAUNCH events.

Correct answer: B

Explanation

Scheduled scaling is the ideal solution for predictable traffic patterns, allowing the Auto Scaling group to proactively increase capacity before the peak demand actually starts. Reactive methods like CloudWatch alarms based on CPU utilization would only trigger after the load increases, potentially causing performance degradation during the initialization of new instances. Manual adjustments or SNS notifications do not provide automated, proactive scaling for known calendar-based events.