You could run SMS on a BDC or a PDC if you want, however; I don't think you would really see much of a difference. The SMS Logon Point has nothing to do with the domain validation of a DC. Yes it would do both, but one wouldn't benifit the other. Also, unless the SMS server is the only DC in your company, only the clients that validate to it would see any benefit. As you can't control which DC clients validate to, it is doubtful you would notice any difference. <br>If you are thinking about automated client discovery and the SMS server discovering clients as they log on, you might see some increase in performance if the BDC/PDC is the only DHCP server (Using the DHCP discovery method in Network discovery),however; as it is unlikely you have only one DHCP server, you most likely wouldn't notice an improvement here either.<br>The other issue that comes to mind is the SQL database. Although you can run SQL on a different box (v7.0) than the SMS server, any performance increase you might have received from the DC you would most likely lose as the SMS server has to communicate with the SQL box across the network. You could choose to run SQL on the DC, but then you will have major performance issues relating to the SQL server.