Hi Jacob, sorry, but I don't understand very well...Router is a hostgroup with all my routers. did you mean remove the hostname ? It will work, however, all routers will monitoring uptime and I need to exclude five. The strange is that it worked up to 4 hosts very well, when I put more one: fail! totally crazy!! I'm lost... <div class="gmail_quote">On Wed, Oct 17, 2012 at 4:50 PM, Jacob Seeley <<a href="mailto:Jacob.Seeley@radispheregroup.com" target="_blank">Jacob.Seeley@radispheregroup.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div link="blue" vlink="purple" lang="EN-US"><div>My guess is you don’t have a host definition for the host (router) you’ve removed – once the undefined hostname was removed from the service definition, it works. -- Jacob <div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in"> From: Leonardo Bacha Abrantes [mailto:<a href="mailto:leonardo@lbasolutions.com" target="_blank">leonardo@lbasolutions.com</a>] Sent: Wednesday, October 17, 2012 3:39 PM To: <a href="mailto:nagios-users@lists.sourceforge.net" target="_blank">nagios-users@lists.sourceforge.net</a> Subject: [Nagios-users] Host exclusion fail more 4 hosts </div><div><div class="h5"> Hey people, I created an group called Routers and I inserted my routers on. I don't want to check uptime of five routers, so, I created the exclusion as: host_name !R1,!R2,!R3,!R4,!R5. The problem is: nagios only work up to four host, because when I add more one host, I received the error below: Error: Could not expand hostgroups and/or hosts specified in service (config file '/etc/nagios/objects/router.cfg', starting on line 13) Error processing object config files! if I remove just one host, it worked. I didn't find anything on manual about limitations. define service{ use generic-service hostgroup_name Routers service_description Uptime max_check_attempts 5 normal_check_interval 10 retry_check_interval 3 contact_groups G-Prod check_command check_snmp!-C Mycommunity -o sysUpTime.0 notifications_enabled 0 host_name !R1,!R2,!R3,!R4,!R5 } Can someone help me please ? many thanks!</div></div></div></div> ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: <a href="http://p.sf.net/sfu/appdyn_sfd2d_oct" target="_blank">http://p.sf.net/sfu/appdyn_sfd2d_oct</a> _______________________________________________ Nagios-users mailing list <a href="mailto:Nagios-users@lists.sourceforge.net">Nagios-users@lists.sourceforge.net</a> <a href="https://lists.sourceforge.net/lists/listinfo/nagios-users" target="_blank">https://lists.sourceforge.net/lists/listinfo/nagios-users</a> ::: Please include Nagios version, plugin version (-v) and OS when reporting any issue. ::: Messages without supporting info will risk being sent to /dev/null </blockquote></div>