The DHCP service is not servicing clients because it has determined that it is not authorized to run.

The DHCP 2000 Server service failed registration and authorization. Therefore, the DHCP 2000 Server is unavailable and cannot serve client requests.

This condition does not repair itself until the error is fixed.

The DHCP service has determined that it is not authorized to run and therefore cannot service any clients.

Possible causes include:

• The DHCP 2000 Server is a member of an Active Directory domain, but it is not authorized in Active Directory.
• The DHCP 2000 Server is a member of a workgroup in an Active Directory domain environment (and it is thus potentially a ‘rogue’ DHCP 2000 Server).
• The DHCP 2000 Server is configured to be authorized in Active Directory but cannot contact a domain controller to confirm authorization.
  

If applicable, use one or more of the following resolutions.

Resolution 1: Authorize the server.

1. Log on to the DHCP 2000 Server as a member of the Enterprise Administrators group, and then open DHCP.
   
2. In the console tree, click DHCP, and then, on the Action menu, click Manage Authorized Servers.
   
3. In the Manage Authorized Servers dialog box, click Authorize, type the name or IP address of the server that you want to authorize, and then click OK. When prompted, click Yes to verify that this is the server name and IP address that you want to add to the authorized list.
   
4. If necessary, in the Managed Authorized Servers dialog box, click Refresh to display the newly authorized server, and then click Close.
   
5. Close DHCP, and then restart (reboot) the DHCP 2000 Server.

Resolution 2: If the server is a member of a Workgroup in an Active Directory environment, do one of the following:

• If you do not want to use this computer as a DHCP 2000 Server, remove it from the network to avoid having it act as a rogue DHCP 2000 Server.
• Join it to the domain, and authorize it (see Resolution 1).

Resolution 3: Investigate whether a network problem prevents the DHCP 2000 Server from contacting Active Directory to confirm authorization:

1. Check the networking configuration of the DHCP 2000 Server by running ipconfig /all at a command prompt. Review the output to confirm that an IP address appears for both DNS servers and Primary WINS Server, and that these IP addresses are correct.
   
2. Use the Nltest.exe tool to confirm that the DHCP 2000 Server can contact a domain controller for the domain, and at the same time (if the DHCP 2000 Server cannot connect to the domain controller) to reset the secure channel, which might resolve the problem.
   
   At a command prompt on the DHCP 2000 Server, type:
   
   nltest /sc_reset:YourDomainName
   
   View the results to check whether the server successfully establishes a secure channel with a valid domain controller.
   
   The Nltest.exe tool is available as part of the Windows Server 2003 Resource Kit Tools at http://go.microsoft.com/fwlink/?LinkId=4544 or the Windows 2000 Resource Kit Tools at http://go.microsoft.com/fwlink/?LinkId=1849.
   
3. Use the Ping.exe tool with a larger than normal packet size to check whether the network connection between the DHCP 2000 Server and its domain controller (which was discovered by using Nltest.exe in the preceding step) is stable. This command can reveal network latency between the two computers.
   
   At a command prompt on the DHCP 2000 Server, type the following command (note that -l is an “el” character, not a one):
   
   ping -l 1000 YourDomainController –n 30
   
   If latency does exist, the Time to Live (TTL) values in the resulting output are very low or packets are dropped from the ping entirely. If high latency is experienced or packets are dropped, use the Tracert.exe tool to trace the route from the DHCP 2000 Server to the domain controller to see where latency occurs. At a command prompt on the DHCP 2000 Server, type:
   
   tracert YourDomainController
   
4. Investigate whether a network problem prevents the DHCP 2000 Server from contacting a domain controller by performing one or more of the following steps:
   
   • Reconnect and check network cabling. If necessary, replace cables.
   • Confirm that the duplex settings on the network adapters within the DHCP 2000 Server match the duplex settings for the switch port or ports.
   • Check other networking hardware, including hardware error logs, that might indicate network adapter problems. If necessary, replace the network adapter.
   • Check that network devices downstream from the DHCP 2000 Server are functioning correctly, including switches and routers.
     
5. Restart the DHCP 2000 Server service.
   
6. Restart (reboot) the DHCP 2000 Server.
   

For more information about other event IDs that are related to DHCP 2000 Server service registration and authorization failure, see DHCP 2000 Server system event IDs 1045, 1046, 1049, 1050, 1051, and 20037.