Auto Scaling groups in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an Auto Scaling group in AWS?

An Auto Scaling group is a collection of EC2 instances managed together to automatically adjust the number of instances based on demand, ensuring availability and cost efficiency.

intermediate

What are the key components of an Auto Scaling group?

Key components include the launch configuration or template, minimum, maximum, and desired number of instances, and scaling policies that define when to add or remove instances.

beginner

How does an Auto Scaling group maintain application availability?

It monitors instance health and automatically replaces unhealthy instances, and adjusts capacity to meet traffic demands, preventing downtime.

intermediate

What is the difference between a launch configuration and a launch template in Auto Scaling groups?

Launch configurations are older and immutable templates for instance settings, while launch templates are newer, versioned, and more flexible, supporting advanced features.

beginner

Why is it important to set minimum and maximum instance counts in an Auto Scaling group?

Setting minimum and maximum limits controls costs and ensures the application has enough resources to handle traffic without over-provisioning.

What triggers an Auto Scaling group to add more instances?

A When instances are healthy

B When the number of users decreases

C When CPU usage exceeds a set threshold

D When the minimum instance count is reached

Auto Scaling groups use metrics like CPU usage to decide when to add instances to handle increased load.

Which AWS service is commonly used to define scaling policies for Auto Scaling groups?

A AWS Lambda

B Amazon CloudWatch

C Amazon S3

D AWS IAM

Amazon CloudWatch monitors metrics and triggers scaling actions based on defined policies.

What happens if an instance in an Auto Scaling group becomes unhealthy?

A The Auto Scaling group stops all instances

B It continues running without changes

C The instance is paused

D It is automatically terminated and replaced

Auto Scaling groups detect unhealthy instances and replace them to maintain availability.

Which of the following is NOT a valid component of an Auto Scaling group?

A Elastic IP address

B Launch configuration

C Scaling policy

D Desired capacity

Elastic IP addresses are not part of Auto Scaling group configuration.

What is the purpose of the desired capacity setting in an Auto Scaling group?

A It sets the target number of instances to run

B It defines the maximum number of instances allowed

C It specifies the minimum number of instances

D It controls the instance type

Desired capacity is the target number of instances the Auto Scaling group tries to maintain.

Explain how an Auto Scaling group helps manage costs and availability for a web application.

Think about how it adds or removes servers to match traffic and keeps the app running smoothly.

Describe the role of launch templates or configurations in Auto Scaling groups.

Consider what information is needed to start a new server automatically.