Active Directory DHCP Authorisation Issues

So you just deleted a DHCP server in your Active Directory site and can’t authorise a new one? Yeah… Stupid.

A client of mine recently deleted a Windows Server running DHCP and couldn’t authorise the new server of the same name.
This is because the client did not Unauthorise the server beforehand. Possibly because the server hardware was dead.

You could get error

The specified servers are already present in the Directory Service

Or this error

DHCP Server not authorized:
Event ID: 1051
Source: DHCPServer
The DHCP/BINL service has determined that it is not authorized to service clients on this network for the Windows domain: Your_Domain_Name.Domain_Root

Here’s a fool proof, yet risky method of sorting the issue out.

  1. Open Active Directory Sites and Services.
  2. Click Services, and then click Net Services. If you can’t see Services, click to select Show Services Node on the View menu.
  3. In the right pane, right-click the name of the DHCP servers that you cannot add to Active Directory, and then click Delete.
  4. Force replication of Active Directory to the other sites, or wait for the replication cycle to be completed.

Now break out AdsiEdit, my favourite tool.

  1. Run AdsiEdit (You may need to install the Windows 2003 Server Support Tools if you’re an AdsiEdit virgin).
  2. Its best practise to run it on a Global Catalog server.
  3. Expand Configuration, expand CN=Configuration, expand CN=Services, and then click CN=NetServices.
  4. Right-click CN=Your_DHCP_Root, and then click Properties.
  5. In the Select a property to view list, click DHCPServers.
  6. In the Values list, click the name of the new DHCP server, click Remove, and then click OK.
  7. Click CN=NetServices, right-click the entry for the new DHCP server, and then click Delete.
  8. Force replication of Active Directory to the other sites, or wait for the replication cycle to be completed.
  9. Reboot the new server. Yeah –  you have to reboot.
  10. Attempt to authorise the server again.

Author: Kieran Barnes

Kieran is a PHP developer with 15 years commercial experience. Specialist in WordPress, CakePHP, CubeCart and all things PHP.

2 thoughts on “Active Directory DHCP Authorisation Issues”

  1. you don’t have to call people stupid. Your method is even too cumbersome.
    Yeah peeps, if you;re reading this, first of all nobody has explosive monopoly to knowledge, we are all trying our best and learning in the daily errors that we make in the procedural course.
    Solution to that problem is Simply go to services and stop the DHCP Server, then go back and re-authorize it, the process should be fine after that.

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