What is the main function of an Auto Scaling Group (ASG)?

The main function of an Auto Scaling Group (ASG) is to automatically adjust the number of Amazon EC2 instances in response to changing demand. This capability allows the application to handle varying workloads efficiently, ensuring that there are enough instances to meet increased traffic while also scaling back when demand decreases to save costs.

With Auto Scaling, you can define scaling policies that dictate how the group should respond to different metrics such as CPU utilization, network traffic, or the number of requests per second. This means the ASG can dynamically increase the number of running instances to improve responsiveness during peak traffic times and decrease the number of running instances when traffic drops, maintaining optimal resource utilization.

In contrast, the other options do not capture the primary role of an Auto Scaling Group. Relocating instances across regions, creating backups, and monitoring network traffic are functions that can be performed by other AWS services but are not the principal purpose of ASGs. For instance, while AWS offers tools for managing backups (like AWS Backup), the ASG’s core competency lies in managing the scaling of EC2 instances according to real-time demand.