Is a Single Domain or Multi-Domain Network Better for an Enterprise?

Question

Computer networks

Actually this is the whole point of the question! For an organization that has a number of branches scattered around the country and a total number of employees of about 500, which network is preferable?!
I would like to hear all the possible pros and cons for a single-domain and multi-domain network under the following mandatory conditions:
1. The domain (root) of the forest must be a virtual server (a mandatory condition (!)), work exclusively under Windows Server 2008 R2;
2. Each branch has its own system administrator, who must be able to create user and computer accounts on his own (without the help and calls to the system administrators of the head Moscow office);
3. Head office sysadmins should be able to control-modify-backup-copy all data;
4. The forest domain must have its own virtual "twin brother" in case of failure;
5. Users from one branch should not be able to register under their credentials on the computers of another branch without the knowledge and permission of the system administrators of the head office;
6. Last on the list and first in priorities - you need to save and transfer all user and computer accounts from the existing single-domain network (!);

Answer 1

It seems to me that single-domain will be easier to manage, all the described points can be implemented.
But the question is to ensure continuous operation and there will be requirements for communication channels. Although, of course, it is possible to put a domain controller in each branch. A multi-domain
structure, in fact, isolated with trust between nodes (domains) is more difficult to manage, but less dependent on communication channels with the head office / branches.
If the channels between branches are reliable and have sufficient bandwidth, then I would choose the first one.

Answer 2

~500 is a lot. Computers are scattered across the country. Uchetki should be transferred from multi-domain.
I advise you to create also a multi-domain.