@scottalanmiller said:
The domain name does remain the same. It's the name of the entire domain. There is no other name at any time.
Every machine in a domain whether a node, a DC member or the forest root all share the same name. So the "rename" happens the moment you join the new server to the domain.
And in DNS, the moment you make it a DC it will have an equal share in the DNS round robin name resolution of the domain.
That makes a little more sense...I think.