Some notifications are caused by durable events. A durable event has a measurable duration; it is active for a period of time (for example, a link failure). Durable events are sent from underlying Managers.
Other notifications are caused by momentary events. A momentary event occurs and is significant for only a specific point in time (for example, an authentication failure event for a device).
Whether an event is durable or momentary is indicated in the Event Type column of your Notification Log Console. (“About notifications” on page 56 includes column descriptions and also severities.)
Sometimes, notifications become outdated (or "stale"). Due to network outages, it is possible that the underlying Managers disconnect from the Global Manager. At this point, a Session Disconnected notification displays to inform the operator that disconnected sources are detected. The notifications from the unavailable sources are not updated in the console. “Responding to disconnected Managers” on page 169 includes additional information.