ADMT and FSMO roles

I recently ran a cross forest ADMT migration, because of subnetting conflicts between the two companies, not all domain controllers were accessible. In order to migrate SID history, the ADMT migration server must contact the FSMO master of the source domain. After several attempts and a sniffer trace, I found this to be true. Specifically its one of the domain level fsmo roles, so I assume it’s the pdc emulator. ADMT 3.2