I have recently migrated a windows 2008 DC to windows 2012 and it is completed.
now 2012 is the GC and demoted the 2008 server. 2008 was the dhcp server and I installed dhsp role in 2012 and unauthorised 2008 server. migrated the dhcp config also to 2012 server.
but dhcp leasing is not working at all and it is giving errors like 1046 and 1056.