Question : Global Catalog Server could not be contacted - AllGc's are down

Help!
I had an old server that ran active director and was my global catalog server.  This server was my only DC.  I put in a new server and made it an additional DC.  I then made the new server the Global Catolog server.  It has control of all 5 masters, and I have corrected DNS.  I then demoted the old server.  The server now takes two hours to boot and after running dcdiag /v I am told that the Global catalog server could not be located - all GC's are down.  I also see in event viewer/Directory services that the Global catalog server could not be found.  Please help

Answer : Global Catalog Server could not be contacted - AllGc's are down

To make it a global catalog server, did you go into Active Directory Sites and Services, and to the NTDS settings and set it as a global catalog server?

After that, you will need to force a replication between the old server and new server in order for the Global Catalog to transfer.

Additionally, take a look at the event logs on both servers to determine what may have gone wrong.