[Nagiosplug-help] strange check_dhcp behavior

[SCHAUSBERGER Christian]

Hi all

Im running Nagios in an Austrian Corporation for quite some time. So far it works fine, but i can´t get the dhcp checks running properly.
I already searched the mailing-list archives and the net, but found noone with a similar problem, so you are my last hope ;)

here´s the problem:

I´m monitoring 2 dhcp servers as a cluster. Nagios checks them correctly and most of the time everything is fine. But every now an then (once or twice per day)
Nagios produces a false alert, because one of the dhcp servers is not responding.  So i wrote a little script that run´s the check_dhcp command permanently and logs the
output. There i found out that around 5 - 10 percent of the requests don´t get an dhcpoffer. So i looked at the dhcp-servers: every single nagios-request appears in the logs
and for every request an offer has been sent. So it is not a network problem. Next I sniffed a little bit of network traffic to see if the dhcp offers actually arive at the nagios host.
And they do. For every request there is an offer logged by tcpdump.
Is it possible that the plugin somehow misses some of the offers?

I´ve tried everything i could think of (including setting longer delays etc.) and nothing worked. 
Does anyone have a clue?

thanks in advance
Christian