Related to

cluster, primary, secondary, resilience, high-availability, failover

Possible solution

There can be many examples of what constitutes Active / Passive monitoring. Below is one example.

Consider that we have a service/process that runs on two servers in an Active/Passive scenario. In this scenario all that matters is that the process must be running on either one server or the other. If the process is not running on either server, then there should be a critical alert. Likewise, if the process is running on both servers, then there should also be a critical alert.

We have created a gateway rule which uses the count() function and Path Alias features to make sure the service count is exactly one. The rule in XML format has been attached for your reference.

Critical scenarios

Both services down on Active and Passive server