We have migrated our DHCP database from Windows 2003 to a new Windows 2012 server, just by using netsh commands, without any problems.
– Install the DHCP Server role on the new 2012 Server, but don’t Authorize it.
– On the Windows 2003 DHCP Server, open CMD and type: netsh dhcp server export C:\dhcp.txt all
– Copy the file to the new 2012 Server (I used C:\)
– On the new 2012 server, open CMD and type: netsh dhcp server import C:\dhcp.txt all
– Done! open dhcpmgmt.msc on 2012 Server, and Voila, there’s your scope. Authorize it, stop the old 2003 DHCP service, and you’re done.