Exam AWS-SysOps topic 1 question 572 discussion

B is correct. https://aws.amazon.com/about-aws/whats-new/2017/07/introducing-target-tracking-scaling-policies-for-auto-scaling/ For example, you can use Auto Scaling to automatically launch EC2 instances for your Auto Scaling group when demand increases to help maintain performance, and terminate instances when demand drops to save money.

The application is heavy on [Memory] so "CPUUtilization" should n't be a correct metric and on the other hand "MemoryUtilization" isn't a built-in Metric so "Request CountPerTarget" is the correct answer.

The RequestCountPerTarget metric measures the number of requests handled by each target (instance or container) behind the ALB. It provides a direct measure of the application's load and is well-suited for scaling policies when the application is memory-heavy, as mentioned in the scenario. By using the RequestCountPerTarget metric, the Auto Scaling group can dynamically scale the number of instances or containers based on the incoming request rate. When the request count increases above a predefined threshold, additional instances or containers can be automatically added to handle the increased load. Conversely, when the request count decreases, the Auto Scaling group can remove instances or containers to optimize resource utilization.

Correct Answer: B

https://aws.amazon.com/about-aws/whats-new/2017/07/introducing-target-tracking-scaling-policies-for-auto-scaling/ With target tracking, you select a load metric for your application, such as “Average CPU Utilization” or the new “Request Count Per Target” metric from Application Load Balancer, set the target value, and Auto Scaling adjusts the number of EC2 instances in your Auto Scaling group as needed to maintain that target.

B is correct. There's a discussion of this that is dated, but I believe is still relevant. https://forums.aws.amazon.com/thread.jspa?threadID=84514

RequestCountPerTarget only keeps a counter of number of requests serviced by an instance, and then triggers after that. So it might help if your app has some memory leak. It does nothing for you if your application servers are going under the load.

Yes. ans B. If you want to go for C then, it should be "Average CPU Utilization"

Thanks Saumen. Appreciate your details that support the answer

it is asking "built-in" service, so CPU utilization should be correct, memory usage - custom monitoring service