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Triggers are logical expressions that are created to represent the current system state.
A trigger may have the following status:
|OK||This is a normal trigger state. Called FALSE in older Zabbix versions.|
|PROBLEM||Normally means that something happened. For example, the processor load is too high. Called TRUE in older Zabbix versions.|
|UNKNOWN||In this case, Zabbix cannot evaluate the trigger expression. This may happen because of several reasons:
- server is unreachable
- trigger expression cannot be evaluated
- trigger expression has been recently changed
Trigger status (the expression) is recalculated every time Zabbix server receives a new value that is part of the expression.
If time-based functions (nodata, date, dayofmonth, dayofweek, time, now) are used in the expression, the trigger is recalculated every 30 seconds.
The expressions used in triggers are very flexible, allowing to create logical tests of various complexity regarding the monitored statistics.