Why Passive Host Check?

[matt.uebel]

We do active host checks for all hosts, and I am trying to figure out why we should have a host check in the NRDS configuration. For instance:

command[__HOST__]=/usr/local/nagios/libexec/check_ping -H localhost -w 200.0,40% -c 400.0,80% -p 1

Is there any reason to continue to have a passive host check if we already have active checks?

[slansing]

Well, if you would like to switch to fully passive monitoring, or you are forced to, this would be a viable option to get a host alive check. If you plan on running the active host ping check then no, there is no need for this.

[matt.uebel]

I am confused as to how we could consider this a valid check. It seems that, if the loopback interface is unresponsive, networking capabilities are dead anyhow, and the client won't actually be able to report back to the server.

Am I missing something?

[matt.uebel]

Is that __HOST__ service necessary for the operation of NRDS? Would we be able to eliminate it from all NRDS configurations without ill-effect?

[scottwilkerson]

It is not necessary at all. You can remove it from the config.

[matt.uebel]

The rest of the NRDS checks initially show up in "unconfigured objects" if there isn't already a matching Nagios Service Object. This NRDS host check seems strange in the way that there doesn't seem to be a matching Object, but it doesn't show up in "unconfigured objects."

What Object does this passive host check map to?

[slansing]

Well it is actively running a ping check to that host, it matches up by the IP/address of the host you are receiving passive checks from. As was said before you can remove the ping check if you wish, it is just a default that we include in many instances when setting up hosts/services.