I have existing DNS infrastructure on BIND servers. For instance I have "test.com" domain.
I want to integrate AD infrastructure in my current infrastructure. My AD should have one domain controller in the same domain: "a.test.com". When I installed first DC and promoted it as a first DC everything was fine. When I promoted second DC I got an error
"DCPromo was unable to create DNS delegation in the parent zone: test.com. This could be because you do not have permissions to do so, or because the zone is hosted by a server that does not run Windows. To ensure thet this domain controller can be found by other computers on the network, you must create a DNS delegation in the parent zone for this domain. To do so, contact an administrator who is responsible for the DNS zone: test.com.
The error was:
The RPC server is unavailable"
These DCs are in different sites.
Why didn't I have this error when I was promoting dc in a.test.com domain? What is the difference between promoting new dc in new domain and promoting new dc in existing domain?