Exam AWS-SysOps topic 1 question 556 discussion

Answer should be A - https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-scaling-simple-step.html#as-step-scaling-warmup With step scaling policies, you can specify the number of seconds that it takes for a newly launched instance to warm up. Until its specified warm-up time has expired, an instance is not counted toward the aggregated metrics of the Auto Scaling group. While scaling out, AWS also does not consider instances that are warming up as part of the current capacity of the group. Therefore, multiple alarm breaches that fall in the range of the same step adjustment result in a single scaling activity. This ensures that we don't add more instances than you need.

Correct Answer is A

both options A and B could be valid reasons for the missing instances in the aggregated metrics, depending on the specific configuration of the Auto Scaling group and the warm-up period settings.

Definitely A because Until its specified warm-up time has expired, an instance is not counted toward the aggregated metrics of the Auto Scaling group. From this link https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-scaling-simple-step.html#as-step-scaling-warmup

i think the question might not be clear enough. if the additional instances are not part of the initial autoscale group, then C is correct. But if the question is referring to the instances scaled up through the policy, then A or B can be the answer. Thus i will lean the answer towards C.

Warmup period - applies to both initiating health checks and then adding to the auto scaling group. So the capacity of the group changes only after the warmup period and successful health check. Cooldown period on the other hand is: to ensure that your Auto Scaling group doesn't launch or terminate additional instances before the previous scaling activity takes effect. So if a scaling activity has been initiated - no new scaling activity will be initiated till the Cooldown period is over.

If you are creating a step policy, you can specify the number of seconds that it takes for a newly launched instance to warm up. Until its specified warm-up time has expired, an instance is not counted toward the aggregated metrics of the Auto Scaling group.

It should be C. It's not a matter warn-up period of an instance if it is not part of auto-scaling group.

A is the answer

Ans is A only ref below link Instance Warm-up If you are creating a step policy, you can specify the number of seconds that it takes for a newly launched instance to warm up. Until its specified warm-up time has expired, an instance is not counted toward the aggregated metrics of the Auto Scaling group. https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-scaling-simple-step.html

A is correct

Hey Yash, correct ans is C. I have verified it as well.