How to create a backup domain controller?

Question

Windows Server

Good afternoon!
I have Windows Server 2016 (it also has a domain controller and a file cleaner) -
I have Windows Server 2012 (installed yesterday) I want to try to make a backup domain controller (in case the main domain controller fails), in connection with this, two questions:
1) Is it possible put a backup domain controller if the server versions are different?
2) Can the manual be more understandable, because. on the Internet, all I found, as a rule, was written: "Adding a server to a domain controller" is unlikely to be related to the backup.

Answer 1

Is it possible to put a backup domain controller if the server versions are different?

It is possible if you currently have the forest level set and the domain level is no higher than 2012. Newer versions of the server are compatible with older domain and forest levels, on the contrary, they are not. Surely your default level is 2016, in this case it will not work. It's easy to level up. Downgrade - I don't know of any other way than to completely demolish the domain and re-upload it. For review, the first googled article that came across:
https://userman.ru/2019/03/26/kak-opredelit-povysi...

"Adding a Server to a Domain Controller"

Hardly anyone wrote that. Either adding the server\PC to the domain, or elevating the role of the computer to a domain controller. The second is what you need. The second controller is no different from the first, the concept of BDC (backup DC) is no longer relevant. A detailed manual is not needed. Just:
0) drive a new server into the domain (if not already);
1) add the AD DC role to the server;
...and that's it :)

Answer 2

The domain controller is not created, but raised.
That is, you need a server in the domain - and it can be promoted to the role of a domain controller.
You need a server in the domain, and then
1. Install the Active Directory Domain Services role.
2. Raise the server to the domain controller (after installing the role in Server Manager, a notification will appear and selecting it - an assistant will appear to raise the server to the DC.
https://www.google.com/search?client=firefox-be&q...