AWS Certified SysOps Administrator – Associate (legacy) — Question 358
An organization has configured Auto Scaling for hosting their application. The system admin wants to understand the Auto Scaling health check process. If the instance is unhealthy, Auto Scaling launches an instance and terminates the unhealthy instance. What is the order execution?
Answer options
- A. Auto Scaling launches a new instance first and then terminates the unhealthy instance
- B. Auto Scaling performs the launch and terminate processes in a random order
- C. Auto Scaling launches and terminates the instances simultaneously
- D. Auto Scaling terminates the instance first and then launches a new instance
Correct answer: D
Explanation
When an EC2 Auto Scaling group determines that an instance is unhealthy, its default behavior is to terminate the unhealthy instance first and then spin up a new instance to replace it. This sequence prevents the group from exceeding its maximum size limit and avoids running duplicate instances simultaneously. Therefore, the termination of the unhealthy resource always precedes the launching of the healthy replacement.