We are having an issue after re-purposing some hardware for use as a DC. The current DC are non R2 server versions this mean when we have come to use DCpromo it has complained. We also want to use this as a second DNS server and stand by DHCP server.
What is the best way to safest way to proceed?
1. We could build a non R2 server
2. We could use the ADPrep tool to update the AD
3. We do 1 and then update to R2
Safest is option 1 as it doesn't involve a schema change and can achieve everything you listed.