I’ve recently did some temporary work on a legacy-environment for a client. This client recently added some 2012 servers as domain controllers and file servers, The only issue was that there was no way that the client could edit Sites and Services to create correct sites and associated subnets, due to a legacy in-house application depending on the default site to contain all domain controllers.
The client only had 2 sites(Belgium and NL) and to resolve this we’ve simply edited the registry on both DC/File servers with the following key:
Name:PreferLogonDC
Type:dword(32 bit)
Value:1
Location:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dfs
Just note that this only does the magic for the default DFS shares NETLOGON, and SYSVOL, and of course I advised the client to stop using that awful in-house application 😉