Launch templates in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Architecture

intermediate

Understanding Launch Template Versioning

You have created an AWS EC2 launch template with multiple versions. You want to ensure that your Auto Scaling group always uses the latest version of the launch template when launching instances.

Which configuration setting in the Auto Scaling group will achieve this behavior?

A Specify the launch template name and set the version to '$Default' in the Auto Scaling group configuration.

B Specify the launch template ID and set the version to '1' in the Auto Scaling group configuration.

C Specify the launch template ID and set the version to '$Latest' in the Auto Scaling group configuration.

D Specify the launch template name and set the version to '0' in the Auto Scaling group configuration.

💡 Hint

Think about how AWS identifies the most recent version of a launch template.

Setting the version to '$Latest' tells the Auto Scaling group to always use the newest version of the launch template. Using a fixed version number like '1' will always use that specific version, ignoring updates.

❓ security

intermediate

Launch Template and IAM Role Association

You want to launch EC2 instances using a launch template that automatically assigns an IAM role to the instances for accessing S3 buckets securely.

Where should you specify the IAM role in the launch template configuration?

A Attach the IAM role directly to the EC2 instances after launch manually.

B In the launch template's 'IamInstanceProfile' section, specify the IAM role name or ARN.

C Specify the IAM role in the user data script of the launch template.

D Assign the IAM role to the VPC where the instances will launch.

💡 Hint

Consider how AWS associates IAM roles with EC2 instances at launch time.

The IAM role must be specified in the 'IamInstanceProfile' section of the launch template. This ensures instances launched from the template automatically receive the role.

❓ service_behavior

advanced

Effect of Changing Launch Template Data on Running Instances

You update the user data script in an existing launch template version and set this new version as the default. What happens to the EC2 instances that were launched using the previous launch template versions?

A The user data script update causes a reboot of all running instances to apply changes.

B All running instances automatically update their user data script to the new version.

C Existing instances are terminated and replaced with new instances using the updated launch template version.

D Existing instances continue running with their original user data; only new instances use the updated user data.

💡 Hint

Think about how launch templates affect instances after they are launched.

Launch templates define instance configuration at launch time only. Updating the template does not affect running instances; only new instances launched after the update use the new data.

❓ Configuration

advanced

Launch Template Network Interface Configuration

You want to create a launch template that launches EC2 instances with two network interfaces: one primary and one secondary. Which configuration in the launch template correctly defines this setup?

A Define two network interfaces in the 'NetworkInterfaces' section, marking one as 'DeviceIndex' 0 and the other as 'DeviceIndex' 1.

B Use the 'SubnetId' field twice in the launch template to create two interfaces automatically.

C Specify only one network interface in the launch template; add the second interface manually after instance launch.

D Create two separate launch templates, each with one network interface, and launch instances from both.

💡 Hint

Consider how AWS identifies multiple network interfaces on an instance.

The 'NetworkInterfaces' section allows specifying multiple interfaces with distinct 'DeviceIndex' values. 'DeviceIndex' 0 is the primary interface, and higher numbers are additional interfaces.

✅ Best Practice

expert

Managing Launch Template Versions for Production Stability

Your team uses launch templates for production EC2 instances. You want to deploy updates safely without affecting running instances and be able to roll back quickly if needed.

Which launch template versioning strategy best supports this goal?

A Create a new launch template version for each update, test it in staging, then update the Auto Scaling group to use the new version only after validation.

B Always use the '$Latest' version in the Auto Scaling group to ensure instances get the newest configuration immediately.

C Delete old launch template versions to keep only the current version for simplicity.

D Edit the default launch template version directly to apply changes instantly to all instances.

💡 Hint

Think about how to minimize risk and enable rollback when updating infrastructure.

Creating new versions and testing before updating the Auto Scaling group ensures stability. Using '$Latest' risks untested changes affecting production. Editing default versions or deleting old versions removes rollback options.