A couple of things to check, did you upgrade your plugins recently? Or changed permisions on check_icmp? Have you tried pinging your hosts on the command line of your nagios system to ensure someone didn't put a firewall in front of you? Are you running Service checks on these hosts? Are they reporting any problems? Could you also reply with the output of nagios -v nagios.cfg. -Zac <div>On 12/30/05, CC Yuen <<a href="mailto:ccyuen@hkcert.org">ccyuen@hkcert.org</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Dear list, I found my Nagios 2.0b4 cannot detect all the hosts suddenly. The screen shown all hosts "DOWN" and cannot be resume. I have checked all the cfg files and tested all the cfg files, I am ensure the config has no problem. Anyone know what's happen? I really have no idea...... Thanks a lot Chung ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! <a href="http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click"> http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click</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">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>