Hi, I am demoting an existing DC that is a GC, and introducing a new DC as a GC. I believe the 2000 exchange server references the DC to be demoted through the RFR reg entry ( not sure why ). How can I demote the existing DC and introduse the new DC as a GC without interruption to clients?Thanks,

Using new hardware? If so, just run both DCs/GC's in paralell, if the old DC is running any FSMO roles be sure to transfer those and dcpromo down the old DC.

Thanks for the reply, "I believe the current 2000 exchange server references the DC to be demoted through the RFR reg entry ( not sure why )."If I run the pair of DC's in parallel, and demote the older server, (and remove the GC role ) exchange will still reference the old server in the RFR entry - which causes all the outlook clients to hang.What should I do?

Did you manually over-ride that? If so ExBPA will tell you and let you know if it'll be a problem.