AWS Certified Solutions Architect – Associate (SAA-C02) — Question 17

A company runs an internal browser-based application. The application runs on Amazon EC2 instances behind an Application Load Balancer. The instances run in an Amazon EC2 Auto Scaling group across multiple Availability Zones. The Auto Scaling group scales up to 20 instances during work hours, but scales down to
2 instances overnight. Staff are complaining that the application is very slow when the day begins, although it runs well by mid-morning.
How should the scaling be changed to address the staff complaints and keep costs to a minimum?

Answer options

• A. Implement a scheduled action that sets the desired capacity to 20 shortly before the office opens.
• B. Implement a step scaling action triggered at a lower CPU threshold, and decrease the cooldown period.
• C. Implement a target tracking action triggered at a lower CPU threshold, and decrease the cooldown period.
• D. Implement a scheduled action that sets the minimum and maximum capacity to 20 shortly before the office opens.

Correct answer: A

Explanation

The correct answer is A because implementing a scheduled action to set the desired capacity to 20 just before office hours ensures that the application has the necessary resources to handle the initial load of users. Options B and C involve dynamic scaling based on CPU usage, which may not effectively anticipate the surge in demand at the start of the day. Option D sets both minimum and maximum capacity to 20, which is unnecessary and could lead to higher costs without addressing the timing issue.