RUNNINGstate, a server offers its services to clients and can operate as a full member of a cluster.
ADMINstate, the server is up and running, but available only for administration operations, allowing you to perform server and application-level administration tasks without risk to running applications. For more information, see ADMIN State.
STANDBYstate, the server listens for administrative requests only on the domain-wide administration port and only accepts life cycle commands that transition the server instance to either the
SHUTDOWNstate. Other administration requests are not accepted. If you specify
STANDBY, you must also enable the domain-wide administration port. See Configure the domain-wide administration port.