I have 4 domain controllers, 1 - 2008 R2, and 3 - 2012 R2, the 2008 R2 domain controller is the original DC. I added the other 3 in order to then demote and send to pasture the 2008 DC. My problem is, when I go to dcpromo the 2008 DC, it's saying that there are no other AD DCs in the domain, and if I remove this one, the domain would no longer exist (paraphrasing). All DCs are replicating to each other. All are global catalog except the 2008 DC. Another funny thing is, when I do Get-ADDomainController | ft Name,isGlobalcatalog on any server, they ALL ONLY show the 2008 DC. If I make the 2008 DC to NOT be a GC server, and i run the command on any of the other DCs, they still bring the 2008 DC up, just saying 'False' as a GC. If I query the site, all DCs will show up as GCs 'TRUE' except the 2008 as False.
Any help would be much appreciated. I really want to decommission the 2008 R2 DC.