You have an Auto Scaling group of Instances that processes messages from an Amazon Simple Queue Service (SQS) queue. The Auto Scaling group scales on the size of the queue. Processing involves a third-party web service. The web service is complaining about the number of failed and repeated calls received from you. When the Auto Scaling group scales in, you have noticed that instances are being terminated while they are processing. What cost-effective solution can you use to reduce the number of incomplete processing?

Answer options:

A.Create a new Auto Scaling group with a minimum and maximum of 2 and instances running web proxy software. Configure the VPC route table to route HTTP traffic to these web proxies.
B.Modify the application running on the instances to enable termination protection while it processes a task and disable it when the processing is complete.
C.Increase the minimum and maximum size for the Auto Scaling group, and change the scaling policies, so they scale less dynamically.
D.Add a lifecycle hook in the Auto Scaling group to put the instances into the Terminating:Wait status when the ASG scales in to finish the ongoing tasks before being terminated.

Answer – D
The following diagram shows the lifecycle of the instances in Autoscaling.
You can put the instances in the Terminating:Wait status to finish the ongoing tasks.
For more information on the Autoscaling Group Lifecycle, please refer to the below link:
http://docs.aws.amazon.com/autoscaling/latest/userguide/AutoScalingGroupLifecycle.html
Option A is incorrect because web proxy software is out of scope and does not help to address this issue.
Option B is incorrect because the application cannot enable termination protection, and we should not stop the instances from being terminated.
Option C is incorrect because this does not address the concern and cannot reduce the number of incomplete processing.