We recently added three new 2012 R2 domain controllers to our environment. We followed all the steps to add them and then remove the three old (2008 R2) DCs. We believed everything was successful until recently when configuring failover for DHCP, the names of the old DCs were listed as options for the partner server. This made us think our metadata had not been cleaned up correctly, so we tried to follow the steps indicated in this article https://technet.microsoft.com/en-us/library/cc816907%28v=ws.10%29.aspx
to clean up the metadata. However, in step 2 the old DCs are not listed as an option for cleanup. I am not sure now whether or not we need metadata cleanup; and if not, why are the old DCs listed when I try to configure DHCP failover?