What is a Central Administration Site (CAS) in SCCM?


Central Administration site is for large organizations having more than 100,000 clients in the hierarchy. Once you have CAS, then you can install primary sites underneath CAS for managing users and devices. Secondary sites can then be installed below primary sites for managing devices over slow connection.

If your organization has less than 100,000 clients, you should only use stand-alone primary sites.

CAS is used for a multi-site hierarchy. This is the first site to be built if you use a multi-site hierarchy. Next layer of site would be primary sites where all processing happens. For smaller organizations, the first site deployed in the hierarchy is a Primary site. But if you want to install more than one Primary site, we can’t install it without a CAS server.

As compared to the previous of SCCM, Primary Site servers can be installed and joined in the Central Site at any point of time. But in SCCM 2012, Primary Site servers can only be connected to the Central Site during installation. This means that the CAS should be installed first before any primary sites in the hierarchy.

Note: We can have maximum 25 child Primary Sites supported by a CAS.

Client data processing is not done by the CAS.

CAS is used for administration and reporting. CAS requires a SQL database to be installed on the site server. CAS support up to 400,000 clients if SQL Server Enterprise or Datacenter is installed on the Central Administration site, and is independent of the SQL Server edition at primary or secondary sites.

Up to 50,000 clients are support if SQL Server Standard is used for the site database at the Central Administration site. This limit remains there even if we upgrade the SQL Server version at the Central Administration site from Standard to Enterprise or Datacenter after installing Configuration Manager.

CAS also doesn’t support client assignment as clients can only be assigned to the primary sites. The reason of this assignment is to let the central site to provide better performance for administration.

Only limited site system roles can be installed on CAS. Management Point (MP) and Distribution Point (DP) can’t be installed in CAS.

 How to decide if we require CAS or not?

While deciding if you should install CAS or not depends upon the number of supported clients in the hierarchy and primary sites.

Install CAS only when:

·         You need to manage more than 100,000 clients or,

·         You need more than one Primary Site server



Changes in Configuration Manager Service Pack 1

With System Center 2012 Configuration Manager Service Pack 1, we can now install a new Central Administration site as a parent site of an existing stand-alone primary site. It means, if you have an existing stand-alone primary site, and you want to connect this site to a newly create central administration site, that is possible with Configuration Manager 2012 SP1. One limitation: only one existing primary site can be expanded into the new hierarchy because the database of the new Central Administration site will be based on the database of your existing stand-alone primary site. We can’t join any other existing primary sites to this site hierarchy, but of course, new primary sites can be installed a child sites below the central administration site.