Why is it possible to login via RDP from one domain to another?

Question

Computer networks

There is a grid with Domain1.local domain.
You need to get access to 1c in an office from another city with the Domain2.local domain The
guys from there sent a ready-made rdp file, but when we enter the Domain2\user login and password, we get the error "credentials used to connect to 1c.domain2.local are invalid .enter new credentials"

Answer 1

did they give you a file that works on their internal network
between your offices, is there a tunnel installed or are you doing vpn there?
if yes, then you need to configure DNS to resolve 1c.domain2.local, if you don’t want to configure DNS by name, specify IP
if not, then the .local zone does not work on the Internet, again, you need to enter an external address instead of a DNS name, perhaps on that side must be configured for port forwarding