IBM Reliable Scalable Cluster Technology (RSCT) is a set of software components that together provide a comprehensive clustering environment for AIX, Linux, Solaris, and Windows operating systems. RSCT is the infrastructure used by a variety of IBM products to provide clusters with improved system availability, scalability, and ease of use. It follows a list of main RSCT components:
Management Domains and Peer Domains 
The set of nodes that is configured for manageability or monitoring is called a management domain of your cluster. The set of nodes that is configured for high availability is called an RSCT peer domain of your cluster.
A peer domain is a set of nodes that have a consistent knowledge of the existence of each other and of the resources shared among them. On each node within the peer domain, RMC depends on a core set of cluster services, which include Topology Services, Group Services and cluster security services.
A management domain is a set of nodes with resources that can be managed and monitored from one of the nodes, which is designated as the management control point (MCP). All other nodes are considered to be managed nodes. Topology Services and Group Services are not used in a management domain.
In order to understand how the various RSCT components are used in a cluster, be aware that nodes of a cluster can be configured for manageability, high availability or both.