Authentication mechanism assurance is a new feature in Active Directory Domain Services (AD DS) in Windows Server 2008 R2. This feature is not enabled by default. It requires a domain functional level of Windows Server 2008 R2 as well as a certificate-based authentication infrastructure and additional configuration. When you enable it, authentication mechanism assurance adds an administrator-designated, universal group membership to a user’s access token when the user’s credentials are authenticated during logon with a certificate-based logon method. This makes it possible for network resource administrators to control access to resources, such as files, folders, and printers, based on whether the user logs on with a certificate-based logon method and the type of certificate that is used for logon.