AWS Certified DevOps Engineer – Professional (DOP-C02) — Question 184

A company uses AWS Directory Service for Microsoft Active Directory as its identity provider (IdP). The company requires all infrastructure to be defined and deployed by AWS CloudFormation.

A DevOps engineer needs to create a fleet of Windows-based Amazon EC2 instances to host an application. The DevOps engineer has created a CloudFormation template that contains an EC2 launch template, IAM role, EC2 security group, and EC2 Auto Scaling group. The DevOps engineer must implement a solution that joins all EC2 instances to the domain of the AWS Managed Microsoft AD directory.

Which solution will meet these requirements with the MOST operational efficiency?

Answer options

• A. In the CloudFormation template, create an AWS::SSM::Document resource that joins the EC2 instance to the AWS Managed Microsoft AD domain by using the parameters for the existing directory. Update the launch template to include the SSMAssociation property to use the new SSM document. Attach the AmazonSSMManagedInstanceCore and AmazonSSMDirectoryServiceAccess AWS managed policies to the IAM role that the EC2 instances use.
• B. In the CloudFormation template, update the launch template to include specific tags that propagate on launch. Create an AWS::SSM::Association resource to associate the AWS-JoinDirectoryServiceDomain Automation runbook with the EC2 instances that have the specified tags. Define the required parameters to join the AWS Managed Microsoft AD directory. Attach the AmazonSSMManagedInstanceCore and AmazonSSMDirectoryServiceAccess AWS managed policies to the IAM role that the EC2 instances use.
• C. Store the existing AWS Managed Microsoft AD domain connection details in AWS Secrets Manager. In the CloudFormation template, create an AWS::SSM::Association resource to associate the AWS-CreateManagedWindowsInstanceWithApproval Automation runbook with the EC2 Auto Scaling group. Pass the ARNs for the parameters from Secrets Manager to join the domain. Attach the AmazonSSMDirectoryServiceAccess and SecretsManagerReadWrite AWS managed policies to the IAM role that the EC2 instances use.
• D. Store the existing AWS Managed Microsoft AD domain administrator credentials in AWS Secrets Manager. In the CloudFormation template, update the EC2 launch template to include user data. Configure the user data to pull the administrator credentials from Secrets Manager and to join the AWS Managed Microsoft AD domain. Attach the AmazonSSMManagedInstanceCore and SecretsManagerReadWrite AWS managed policies to the IAM role that the EC2 instances use.

Correct answer: B

Explanation

Option B is the most operationally efficient solution as it uses tags to target specific instances for joining the domain, leveraging AWS Systems Manager's automation capabilities. Options A and C involve additional complexities with SSM documents and runbooks that can complicate maintenance. Option D requires handling sensitive credentials in user data, which can pose security risks.