Check out the passive check protocol. Nagios has tons of features like that which you need to understand in order to get it to scale. The default out of the bo

Check out the passive check protocol. Nagios has tons of features like that which you need to understand in order to get it to scale. The default out of the box config is something you monitor a handful of machines with, but Nagios is regularly run with 100k+ active checks. That requries some careful architecting.