Central Administration Site

Another type of site that has been around in previous versions of ConfigMgr is the central site server. A central site server is the one at the top of a hierarchy and is used to centrally administer the entire Configuration Manager implementation. Because of its role in hierarchy-wide management, a central site typically should not have clients directly assigned (although it is possible). Further, because all information in the hierarchy resides at the central site, this is typically the key site in the hierarchy where reporting is configured.
 

The central site server is no longer present in Configuration Manager 2012 R2. It has been replaced by a new type of site server known as a Central Administration Site (CAS). The CAS is much like the central site server except that it cannot have any clients assigned (not even an option), some site functions are not available at the CAS (such as most of the discovery options), and the CAS must be installed as the first site of the hierarchy. However, if you decide not to install the CAS until your organization has reached a desired limit of clients, you can expand your stand-alone primary site into a CAS only one time.

As we mentioned, sites manage clients. To facilitate client management and depending on the services being delivered, several different functional roles must be in place at the site. These functional roles are either added to the site server itself or configured on external servers. Either way, the servers that host these support roles are known as site systems. The option for distributed site servers to fulfill various functions allows for very flexible and scalable designs. Ultimately, the decision on where to place these site systems or whether to use external site systems at all is up to the administrator. And, if these roles need to be moved to other serversafter installation, or other servers need to be added, that is easy to do. This work is performed in the Administration workspace, under Site Configuration of the Configuration Manager console, as shown in Figure