The InvocationId element contains the GUID that represents the domain containing the domain controller.

 <xs:element name="InvocationId" type="ser:guid" />

The InvocationId element is populated from the nTDSDSA!invocationId attribute of the nTDSDSA object specified by the GetADDomainControllerRequest/NtdsSettingsDN (section input parameter element. If the nTDSDSA!invocationId attribute is not present or cannot be read due to the client lacking access rights to read the attribute, the server populates the ActiveDirectoryDirectoryServer/InvocationId element with a value of 00000000-0000-0000-0000-000000000000.