(1) In OSI X.400, a set of one or more message transfer agents and zero or more user agents that make up a system capable of handling messages and is managed by either an administration or private company.
(2) A set of nodes that are configured for management by Cluster Systems Management. Such a domain has a management server that is used to administer a number of managed nodes. Only management servers have knowledge of the domain. Managed nodes only know about the servers managing them.
(3) An area of knowledge relative to providing control over, and information about the behavior, health and life cycle of manageable resources.