The SubordinateReferences element contains an array of distinguished names of subordinate references (referrals) (see [RFC3296]) that this directory service returns.

   name="SubordinateReferences" nillable="true" type="sera:ArrayOfstring" />

The SubordinateReferences element is populated from the domainDNS!subRefs multivalued attribute on the domain NC root object ([MS-ADTS] section If the domainDNS!subRefs attribute is not present or cannot be read due to the client lacking access rights to read the attribute, the server returns a null ActiveDirectoryPartition/SubordinateReferences element.