A failover cluster is a group of server computers that work together to maintain high availability of applications and services. The server computers may also be referred to as “servers” or as “nodes”. If one of the nodes fails, then another node in the cluster can take over its workload with little or no downtime, a process which is known as “failover”.
In some computing architectures, a group of computers that share a network resource database and have a common security policy are called a “domain”. A domain may have a domain controller, sometimes called a “primary domain controller” (PDC) which is a computer that manages the resource and user access for the entire domain. One or more backup domain controllers may also be present. Other computers in the domain are workstations or servers that provide computational resources to domain users, after domain authentication or another authentication protocol establishes that the users have permission to access the computers in the domain. A domain administrator may manage access using administrative software and security policies.