You are having a web and worker role infrastructure defined in AWS using Amazon EC2 resources. You are using SQS to manage the jobs being sent by the web role. Which of the following is the right way to ensure the worker processes are adequately set up to handle the number of jobs sent by the web role?

Answer options:

A.Use Cloudwatch monitoring to check the size of the queue and then scale out SQS to ensure that it can handle the right number of jobs.
B.Use ELB to ensure that the load is evenly distributed to the set of web and worker instances.
C.Use Route53 to ensure that the load is evenly distributed to the set of web and worker instances.
D.Use Cloudwatch monitoring to check the size of the queue and then scale out using Autoscaling to ensure that it can handle the right number of jobs.

Answer - D
The below diagram shows how SQS can be used to manage the communication between the Web and worker roles. The number of messages in the SQS queue can be used to determine the number of instances that should be there in the AutoScaling Group.
For more information on SQS and Autoscaling, please refer to the below URL:
http://docs.aws.amazon.com/autoscaling/latest/userguide/as-using-sqs-queue.html