D. Join the file system to the Active Directory to restrict access. Joining the FSx for Windows File Server file system to the on-premises Active Directory will allow the company to use the existing Active Directory groups to restrict access to the file shares, folders, and files after the move to AWS. This option allows the company to continue using their existing access controls and management structure, making the transition to AWS more seamless.

D. allows the file system to leverage the existing AD infrastructure for authentication and access control. Option A is incorrect because mapping the AD groups to IAM groups is not applicable in this scenario. IAM is primarily used for managing access to AWS resources, while the requirement is to integrate with the on-premises AD for access control. Option B is incorrect because assigning a tag with a Restrict tag key and a Compliance tag value does not provide the necessary integration with the on-premises AD for access control. Tags are used for organizing and categorizing resources and do not provide authentication or access control mechanisms. Option C is incorrect because creating an IAM service-linked role linked directly to FSx for Windows File Server does not integrate with the on-premises AD. IAM roles are used within AWS for managing permissions and do not provide the necessary integration with external AD systems.

When you create a file system with Amazon FSx, you join it to your Active Directory domain to provide user authentication and file- and folder-level access control.

D is relevent and accurate answer when we consider this: https://docs.aws.amazon.com/fsx/latest/WindowsGuide/creating-joined-ad-file-systems.html "When you create a new FSx for Windows File Server file system, you can configure Microsoft Active Directory integration so that it joins to your self-managed Microsoft Active Directory domain. To do this, provide the following information for your Microsoft Active Directory"

The on-premise AD already has restrictions via group in place so D makes no sense as the groups are already linked to file system. "The company must ensure that the on-premises Active Directory groups restrict access to the FSx for Windows File Server SMB compliance shares, folders, and files after the move to AWS." The question is about linking the on-prem permissions to the new FSx server on AWS and this can only be done by A

Option A: Creating an Active Directory Connector and mapping groups to IAM groups is more relevant for AWS Directory Service, such as AWS Managed Microsoft AD, and not for integrating with existing on-premises Active Directory. Option B: Using tags is typically not used for access control purposes. Tags are metadata and are not directly involved in user authentication and authorization. Option C: Creating an IAM service-linked role directly linked to FSx for Windows File Server is not the standard approach for integrating with existing on-premises Active Directory.

https://docs.aws.amazon.com/fsx/latest/WindowsGuide/self-managed-AD.html

This allows the on-premises Active Directory to manage permissions to the FSx file shares, meeting the key requirement to use existing AD groups to control access after migrating to AWS. Joining FSx to the AD domain allows the native file system permissions, users, and groups to be applied from Active Directory. Access is handled seamlessly via the trust relationship between FSx and AD. The other options would not leverage the existing AD identities and groups

The AD is on-premisses... Your need the connector.

https://docs.aws.amazon.com/fsx/latest/WindowsGuide/aws-ad-integration-fsxW.html

Other options are referring to IAM based control which is not possible. Existing AD should be used without IAM.

https://aws.amazon.com/blogs/storage/using-amazon-fsx-for-windows-file-server-with-an-on-premises-active-directory/

Answer D. Amazon FSx does not support Active Directory Connector .

https://docs.aws.amazon.com/fsx/latest/WindowsGuide/self-managed-AD.html

Note: Amazon FSx does not support Active Directory Connector and Simple Active Directory. https://docs.aws.amazon.com/fsx/latest/WindowsGuide/aws-ad-integration-fsxW.html

The answer will be AD connector so : A, it will create a proxy between your onpremises AD which you can use to restrict access

Option D: Join the file system to the Active Directory to restrict access. Joining the FSx for Windows File Server file system to the on-premises Active Directory allows the company to use the existing Active Directory groups to restrict access to the file shares, folders, and files after the move to AWS. By joining the file system to the Active Directory, the company can maintain the same access control as before the move, ensuring that the compliance team can maintain compliance with the relevant regulations and standards. Options A and B involve creating an Active Directory Connector or assigning a tag to map the Active Directory groups to IAM groups, but these options do not allow for the use of the existing Active Directory groups to restrict access to the file shares in AWS. Option C involves creating an IAM service-linked role linked directly to FSx for Windows File Server to restrict access, but this option does not take advantage of the existing on-premises Active Directory and its access control.