Software :: Manually Executing Entry In Nagios Checkcommands.cfg

First I don't know Nagios. I've been left with a fairly large(350 servers, 750 services) Nagios system installed. I've scraped and googled till I'm blue in the face. The Nagios folks have been less than helpful in that they tell me I need to figure it out myself. I've tried for four days to *figure it out myself*.

I have an entry in the checkcommands.cfg file:

# 'check_dns_external' command definition
define command{
command_name check_dns_external
command_line $USER1$/check_dns -H $HOSTNAME$ -t 60 -s 4.2.2.1 -a $HOSTADDRESS$
}

First, I don't understand what this command means and does. Next, I don't understand how to manually execute this command. I do know that the command in automatic mode has stopped working as Nagios tries to execute and I get an error message on the Service Status Types: Nagios alert page. The alert doesn't come with any regularity as to time of day or availability of resources. Apparently, this Nagios command is executing randomly. It is waking me up several times a night and several times a day as we page out alerts via email.

I'm lost. Aside from bouncing the entire Nagios stack, which is not possible right away as this is a Production system, is there any way to manually execute the offending line described above? Again, I've asked the Nagios folks and they have declined to answer.