
To ensure that KDC support for claims, compound authentication, and Kerberos armoring is enforced in the child1.contoso.com domain, you need to upgrade the domain controllers in that specific domain to at least Windows Server 2012 R2 and raise the domain functional level of childl.contoso.com to Windows Server 2012 R2. Upgrading DC11 to Windows Server 2012 R2 will fulfill the part of ensuring the domain controllers are of the required version. Then, raising the domain functional level of the child domain (child1.contoso.com) will establish the necessary environment to support these features. There is no direct requirement to upgrade the root domain's functional level or its domain controllers for enforcing these features in the child domain.


