Computers that are unable to locate a domain controller for their domain won't be able to log on and won't be able to process user logons. Troubleshooting the domain controller location process is a key part of solving many logon problems.
Symptoms of a client's inability to locate a domain controller include an inability to log on to the domain and an inability to process user logons. You might also see System and Security event log messages indicating that a domain controller for the appropriate domain could not be found.
To determine the cause of the problem, follow these steps:
Assuming that your client computer has a proper network configuration and is otherwise able to connect to a domain controller (using ping, for example), the problem is most likely in your DNS resource records, or your domain controller is not functioning properly.
If DNS does not contain the proper records, restart a domain controller. Doing so should reregister the domain controller in DNS; if it fails to do so, then either DNS is at fault or that particular domain controller has failed. Verify that other domain controllers can register with DNS. If they cannot, replace your DNS server. If they can, the original domain controller has failed and might need to be removed from the network.
If DNS contains the proper records, but a domain controller continues to not respond to client requests, restart the domain controller. If doing so fails to correct the problem, you will most likely need to demote the domain controller to a member server, then reinstall Active Directory by re-promoting the server.
Note that very few client-side conditions exist other than basic network misconfiguration that prevents a client from locating a domain controller. Most of the problems are in the DNS server or with a domain controller that fails to respond to a client's initial requests.