What should a solutions architect do to maintain the desired performance across all instances m the group?

An application runs on Amazon EC2 instances across multiple Availability Zones The instances run in an Amazon EC2 Auto Scaling group behind an Application Load Balancer The application performs best when the CPU utilization of the EC2 instances is at or near 40%

What should a solutions architect do to maintain the desired performance across all instances m the group?
A . Use a simple scaling policy to dynamically scale the Auto Scaling group
B . Use a target tracking policy to dynamically scale the Auto Scaling group
C . Use an AWS Lambda function to update the desired Auto Scaling group capacity
D . Use scheduled scaling actions to scale up and scale down the Auto Scaling group

View Answer

Answer: B

Explanation:

Reference: https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-scaling-target-tracking.html

"With target tracking scaling policies, you select a scaling metric and set a target value. Amazon EC2 Auto Scaling creates and manages the CloudWatch alarms that trigger the scaling policy and calculates the scaling adjustment based on the metric and the target value. The scaling policy adds or removes capacity as required to keep the metric at, or close to, the specified target value. In addition to keeping the metric close to the target value, a target tracking scaling policy also adjusts to changes in the metric due to a changing load pattern. For example, you can use target tracking scaling to: Configure a target tracking scaling policy to keep the average aggregate CPU utilization of your Auto Scaling group at 40 percent. Configure a target tracking scaling policy to keep the request count per target of your Application Load Balancer target group at 1000 for your Auto Scaling group."