I'm hoping someone can help me. I'm doing some testing and setup a backup domain controller. Didn't do anything special (just ran through the basic wizard) other than setup a couple of forwarders to forward internet traffic to opendns (which is the same as the primary domain controller). When i shutdown the primary domain controller i'm having problems accessing the domain. For example i have some mapped drives to other machines on the network. When i click one of the drives it comes up with an "enter network password" dialog and if i do enter my credentials it works but if of course i shouldn't have to do this. Also if i do a gpupdate i get the following error:
Computer policy could not be updated successfully. The following errors were encountered: The processing of Group Policy failed because of lack of network connectivity to a domain controller. This may be a tran sient condition. A success message would be generated once the machine gets connected to the domain controller and Group Policy has successfully processed. If you do not see a success message for several hours, then contact your administrat or.
Apparently the DNS is still working fine on the backup domain controller because i changed it to my only dns entry and i can still access the internet.
Both Domain Controllers are running Server 2012 Core. Both are running DNS. i've also checked the NTDS settings on both and they are set as "Global Catalog". All the macines have their primary dns as the primary domain controller and their second dns as the backup domain controller.