Perhaps the most common error message you are likely to see in Windows networking is that the domain controller could not be contacted during a logon attempt. This message tells you almost nothing about why you can't log on, but it does tell you that your connection to a domain controller could not be established. The reason(s) can be one or many, and either hardware and software in origin. Here are some steps to diagnose this common problem.
First, check that your domain controller is indeed operating, and that other connections to clients are established and working. If so, check your domain spelling in the login dialog box (a different error message appears when the password is wrong but the account can be located). Then begin by eliminating hardware issues. Check your network connections to see if your hub and your NIC card lights have the lit as they should be. If not, establish the connection.
That's the basic hardware possibility, and it's really basic. But it could be that the overnight cleanup crew managed to disconnect the workstation somehow, so check it. If that doesn't solve the problem, then log onto your client locally (this machine) using an administrator's account and password. Open a command prompt (Start, Run, then enter cmd) and give an IPCONFIG command. This will tell you if you have the correct IP address, if your system was able to acquire an IP address by DHCP.
With the command prompt open, next use PING to contact your domain controller and one or two other systems on your network. Try using both friendly names (is DNS working), and IP addresses as arguments to PING. If you can PING successfully, that's reassurance that you are looking at a software problem.
Now open the Properties dialog box of My Computer and click on Computer Name. Then click on Network ID to launch the wizard. Try reconnecting to your network by entering the name of the computer and domain again. This sometimes solves the problem, but if not, try deleting the machine account at the domain server and then use the Network ID wizard to rejoin the domain again.
If you are unable to rejoin your domain, unable to PING or IPCONFIG correctly you can also try to delete your Network protocol (TCP/IP) and reinstall it. Then try rejoining your domain.
In most cases the steps above will solve 98% of the problems you are likely to encounter.
If you have users whom you trust with all these steps, you might create a checklist for dealing with this situation, and distribute to those users. This could save you a lot of calls because of failed logins, and take a load off the trouble desk.
Barrie Sosinsky is president of consulting company Sosinsky and Associates (Medfield MA). He has written extensively on a variety of computer topics. His company specializes in custom software (database and Web related), training and technical documentation.
- While I agree with most of the suggestions given - the BEST resource of all was overlooked! After using the IPCONFIG and Ping commands to ensure your IP stack is working and obtained the correct settings, use the event viewer. This will indicate errors, duplicate names on the network, and give you an "insiders" look to what may have occured. — Susan J Bourbeau