Ideally, Azure AD Connect should be installed on a dedicated domain-joined server, but you can also install it on your domain controller.
If I want to sync two different forests then my question is which forest's domain-joined server should be used to install AAD-Connect ??
On that note, is it possible to install Azure-AD connect on totally separate Windows Server which is NOT joined to any of the two forests ??
In this case when I am configuring Azure-AD connect, since all the 3 servers (two forest-servers and one AADC-server) are on the same subnet, would AADC-wizard able to access the domain-controllers ?
Thanks.