There are many situations in which you might want to have more than one Nagios instance monitoring your IT infrastructure. One reason can be a firewall blocking all but a few machines in your company. Another reason would be the need to load-balance all checks so that they don't require an enterprise-class server. Other people may need to monitor machines in different physical locations from separate machines to be able to check what is wrong within a branch, even if the links to central servers are temporarily down.

Regardless of the reason, you may need, or want the execution of checks to be split across multiple computers. This type of setup might sound complicated and hard to configure, but with Nagios, it is not as hard as it seems. All that's necessary is to set up multiple Nagios instances along with the NSCA agents or daemons.

There are subtle the various in how the various instances need to be configured. Usually, there are one or more Nagios instances that...