Mastering Active Directory - Second Edition

Single domain model

A single domain model contains the single-domain-single-forest structure. It is easier to administer and has a lower cost to implement. When we set up the Active Directory infrastructure for the first time, it will be in this single domain model by default. The domain will become the root domain for the forest by default, and all the objects will be stored in there:

In this mode, all the directory data will need to be replicated to all the available domain controllers. It doesn't matter if it's in a different geographical location. The user can use any available domain controller to authenticate into any system or resources. ...