Auto Scaling groups in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

How does an Auto Scaling group handle instance health checks?

An Auto Scaling group monitors the health of its instances. What happens when an instance fails a health check?

A The instance is terminated and replaced with a new one automatically.

B The instance is rebooted but not replaced.

C The instance is left running but marked unhealthy in the console.

D The Auto Scaling group pauses scaling activities until manual intervention.

💡 Hint

Think about how Auto Scaling keeps your application healthy without manual work.

Auto Scaling groups automatically terminate unhealthy instances and launch new ones to maintain the desired capacity and health of your application.

❓ Architecture

intermediate

What is the effect of setting the minimum size to 3 and maximum size to 5 in an Auto Scaling group?

You configure an Auto Scaling group with a minimum size of 3 and a maximum size of 5. What does this configuration guarantee?

A The group will launch exactly 4 instances at all times.

B The group will always have at least 3 instances and never more than 5 instances running.

C The group can scale down to zero instances if demand is low.

D The group will launch 5 instances immediately and never scale down.

💡 Hint

Minimum and maximum sizes define the boundaries for scaling.

The minimum size ensures the group never has fewer than 3 instances, and the maximum size prevents it from exceeding 5 instances.

❓ security

advanced

Which IAM permission is required to allow an Auto Scaling group to launch EC2 instances?

To enable an Auto Scaling group to launch EC2 instances, which IAM permission must be granted to the Auto Scaling service role?

A autoscaling:UpdateAutoScalingGroup

B autoscaling:CreateLaunchConfiguration

C ec2:RunInstances

D ec2:TerminateInstances

💡 Hint

Launching instances requires permission to start EC2 instances.

The Auto Scaling service role needs the ec2:RunInstances permission to launch new EC2 instances as part of scaling activities.

❓ Configuration

advanced

What happens if you set the desired capacity higher than the maximum size in an Auto Scaling group?

You configure an Auto Scaling group with a desired capacity of 6 but set the maximum size to 5. What will be the actual number of instances running?

A The group will launch 1 instance and wait for manual scaling.

B The group will launch 6 instances, ignoring the maximum size.

C The group will launch 0 instances due to configuration conflict.

D The group will launch 5 instances, respecting the maximum size limit.

💡 Hint

Maximum size limits the upper bound of instances regardless of desired capacity.

The Auto Scaling group enforces the maximum size limit and will not launch more than 5 instances even if desired capacity is set higher.

✅ Best Practice

expert

Which strategy best ensures zero downtime during Auto Scaling group instance replacement?

You want to replace instances in an Auto Scaling group without causing downtime. Which approach achieves this?

A Use rolling updates with a health check grace period and minimum healthy percentage set above 50%.

B Terminate all instances at once and then launch new ones immediately.

C Manually stop instances one by one without updating the Auto Scaling group.

D Set desired capacity to zero before launching new instances.

💡 Hint

Think about how to keep enough healthy instances running during updates.

Rolling updates with a health check grace period and a minimum healthy percentage ensure new instances are healthy before old ones are terminated, preventing downtime.