If you get yourself into trouble with DNS on a domain controller you might sit on the "Preparing Network Connections..." screen for quite some time. By make a mess i mean - you have a DC pointing to a DNS server that is down (with no alternate), or maybe you modify the Domain Controllers IP address without following the proper procedure. There are others that will get you into this rut, but they are the two that come up frequently.
In my specific example i changed the IP address scheme on my domain controllers to suit my home network. After doing so the domain controllers took 20 minutes to get themselves ready, and DNS wouldnt start because it was waiting on inital synchronization. DNS Event 4013 was all through the logs. And when i attempted to use the DNS console it informed me that DNS was not running on this computer.
Event Type: Warning
Event Source: DNS
Event Category: None
Event ID: 4013
Computer: <computer name>
Description:The DNS server was unable to open the Active Directory. This DNS server is configured to use directory service information and can not operate without access to the directory. The DNS server will wait for the directory to start. If the DNS server is started but the appropriate event has not been logged, then the DNS server is still waiting for the directory to start.
Fortunately there is a way to tell DNS to get on with things and not wait for AD. The following reg key instructs AD not to wait for initial synchronization from a peer, and lets DNS load the zones from AD without the initial sync. Its not a great plan for for production forest, but its handy when you make a mess of your lab.
Value name: Repl Perform Initial Synchronizations
Value type: REG_DWORD
Value data: 0
Once the key is set i reboot the domain controller, log in and clean up DNS.
Once things are back to normal it is important to remove the the key to return AD to its normal behaviour. Also, dont do this in your production environment - call Microsoft support and have an engineer see if there is a better way to get things working for you. There might be other issues you will make much worse if you use this key.