A master control server is the server that controls all other servers in the cluster. It is the first server in the cluster and contains the primary installation of HC. The master control server constitutes the main backbone of HC. It is responsible for performing or routing provisioning tasks. It also contains HC DB, APIs and task scheduler. Being a control server it contains all the three components of the HC Primary installer namely:

1. Portal
2. API
3. Provisioning Services and centrally controls all other roles in the cluster.

Select Control Servers to add a master control server. Specify control server credentials and click Check Connectivity. Once you are connected successfully, only then you can add a master control server.