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DHCP not working

Last Modified: 2012-08-21
I am moving my AD from Server 2003 to Server 2008 R2.  I have the two new 2008 servers up, DCpromo so they are DCs and DNS servers.  I now have 4 DCs with  the 5 FSMO services moved over to one of the new servers with DHCP on one of the 2003 servers.  

I attempted to move the DHCP from the 2003 server to the 2008 server.  I installed the DHCP role on the new 2008 server but did not configure it.  Deleted the DHCP database off the new server.  I exported the DHCP database using the export, all switch in the netsh command.  Stopped and disabled the DHCPserver  service on the 2003 server and imported the database into the new server.  Restarted the DHCPserver service.

Everything looked good.  I only had a ndsregister warning which I resolved.  The DHCP logged was renewing IP addresses (IPV4), no error message and my virtual desktops were picking up IP addresses.  I went home feeling good.

The next morning I receive a call that devices were not picking up IP address.  I had the tech stop the DHCPserver services on the 2008 server and restart the DHCPserver service on the  previous 2003 server.  Everything good except a few IP address conflicts which I expected since the database on the old 2003 server had not been updated for 18 hours.

The one thing I can think of missing is the authorize DHCP server.  I did not know to unauthorized the 2003 server.  When the tech moved DHCP back to the old 2003 server, he noticed that the new 2008 server and the old 2003 server both were authorized and removed the new 2008 server from the list.

I cannot find any error or warnings in the logs.  The DHCP logs on the 2008 server showed renewals etc up to the time the service was stopped with on errors.  The old 2003 DHCP logs show renewal etc from the time the old DHCP service was restarted, no errors.  The one interesting thing is, there was no problems with devices on the same side of the router as the DHCP server.  All the DHCP issues were at locations on the other side of the router but not all.  I was showing some devices on the 2008 logs before the service was stopped.

The only thing I can think of is that the old server was still a registered DHCP.  The device was asking for an IP address, saw the old 2003 server was registered to be a DHCP server and when it could not it, failed.  I do not know how the device queries for an address.  Does this make since?  I would like to have a better feeling about this before I attempt this again.

Thanks for any ideas.

Larry K. Meyer
Network System Specialist
Kent District Library
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