One of the beautiful feature in Nagios is notification interval.
notification_interval directive is used to determine the interval at which notifications should be made while this escalation is valid.
If you specify a value of 0 for the interval, Nagios will send the first notification when this escalation definition is valid, but will then prevent any more problem notifications from being sent out for the host.
If notification_interval is grater than 0 (Eg: notification_interval 10)Notifications are sent out for every 10 minutes until the host recovers.
Note: If multiple escalation entries for a host overlap for one or more notification ranges, the smallest notification interval from all escalation entries is used.
In general configuration looks like below:
# Generic host definition template – This is NOT a real host, just a template!
name generic-host ; The name of this host template
notifications_enabled 1 ; Host notifications are enabled
event_handler_enabled 1 ; Host event handler is enabled
flap_detection_enabled 1 ; Flap detection is enabled
failure_prediction_enabled 1 ; Failure prediction is enabled
process_perf_data 1 ; Process performance data
retain_status_information 1 ; Retain status information across program restarts
retain_nonstatus_information 1 ; Retain non-status information across program restarts
register 0 ; DONT REGISTER THIS DEFINITION – ITS NOT A REAL HOST, JUST A TEMPLATE!
In above example you can find notification_interval as 0, that means all people in admin group will get alert when a service status is changed.