The attribute nTMixedDomain is present on each domain NC root object. The value of this attribute MUST be 0 or 1. The value 1 indicates a domain that is in mixed mode and that supports replication to Windows NT operating system backup domain controllers ([MS-NRPC]). The value 0 indicates a domain that does not support such replication.
If the value of nTMixedDomain is 0, it cannot be changed.
The attribute nTMixedDomain on a crossRef object is read-only and equals the attribute nTMixedDomain on the corresponding domain NC root object.
If there are Windows Server 2008 operating system or later DCs in the domain, nTMixedDomain MUST be 0. This implies that Windows Server 2008 and later DCs cannot be used in a domain that is in mixed mode.