What is the tiering ?

The three-tier architecture of an Active Directory is an infrastructure architecture that separates the different parts of a network into three distinct layers. This architecture has been recommended by Microsoft for many years for Active Directory-based infrastructure and is widely used in companies of all sizes.

There is no specific reference that requires the implementation of this architecture, but it is often considered a solid network design practice and recommended for most businesses.

The advantage of three-tier architecture is that it is deployable on all the infrastructure you will encounter.

It is a proven model that has evolved to incorporate the Cloud, but it remains a foundation to be set up in your infrastructure.