looking to reinstall DHCP server(Serv-A) from 2012 to 2012R2 with same name and IP. This is partner server in dhcp relationship of two servers.
2nd partner(Serv-B) is already on 2012R2(installed couple of months before). MCLT of failover relationship is 1 hour and it is in load balance mode. Enable message authentication is checked with shared secret.
Now question is
1-)Is it necessary to remove relationship before demoting serv-A as the installation will took more than 1 hour?
Reason this is bothering me to have 2nd opinion is, last time when i was rebuilding serv-B from 2012 to 2012R2, i didnt break failover relationship between DHCPs. every configuration remain the same post promotion(i.e: IP, hostname, new certs in personal store). but under the failover status for partner server, it said: state of the server :DOWN
So then i had to remove relationship and add both servers(New and Old) in new relationship, and replicate scopes from Serv-A to Serv-B to make them work in load balance mode onwards.
Looking for some guidelines around my question and best way of achieving this task.