AWS Certified Solutions Architect – Professional — Question 598

You have just added a new instance to your Auto Scaling group, which receives ELB health checks. An ELB heath check says the new instance's state is out of
Service.
What does Auto Scaling do in this particular scenario?

Answer options

• A. It replaces the instance with a healthy one
• B. It stops the instance
• C. It marks an instance as unhealthy
• D. It terminates the instance

Correct answer: C

Explanation

When an ELB health check determines that an instance is OutOfService, Auto Scaling's immediate response is to mark the instance as unhealthy. Once marked unhealthy, Auto Scaling will subsequently schedule the instance for termination and replacement, but the direct initial step is changing its health status.