This is how our network was set up...
Main HQ with three branches. We were going to have the TLD as company.local and then subdomains for each branch including a subdomain for HQ, which would be hq.company.local. We went so far as to create the subdomain hq.company.local on a 2008 R2 box but never wound up using it. The DC for hq.company.local has been powered off since April 2011. AD Sites and Services indicates that AD Connections exist between hq.company.local and the TLD DCs as well as the other subdomain DCs. We want to now remove the hq.company.local subdomain. I just powered it back on and tried to run the AD replications to it manually using ADSS, which failed.
Since AD replication is failing to hq.company.local, I'm assuming that if I demote the hq.company.local domain controller that AD throughout the entire company will not reflect that the hq.company.local subdomain has been removed.
Not quite sure where to start here in getting hq.company.local fully removed from my forest, which is in 2003 mode since all 3 TLD DCs are 2003 x64 Enterprise. Any suggestions?