Understanding state flapping.
Flapping occurs when a service check changes its state too frequently between OK and ALARM state.
Such checks or behavior may result in a storm of notifications mails/sms. Which in short is not the desired or correct way of monitoring.
In order to avoid this nagios self check and minimizes the flapping result by self analysis and suppressing the alerts of such services till they pass or come out of flapping state.
For this nagios self checks the history of past 21 hosts/services and does a self analysis to check which of the services are changing their state too frequently and suppress their alerts by keeping them under observation known as “Flapping state”