Soft and hard states of alerts.
There are 2 kinds of service states in Nagios known as soft and hard states.
Soft state - This occurs when the check has resulted in “not ok ” or “down” before the max_check_attempts defined is completed.
Also, when a service recovers within this limit it is known as soft_recovery.
Event handlers can be triggered whenever such states are received for rectification.
Hard state - If re_checked attempts have already been passed and the service hasn’t come UP.
When the service check state shows “DOWN” due to respective HOST is either DOWN or not reachable.
Logging is done for hard state and notifications are sent via mail, SMS, etc. to respective contact groups to take necessary actions.