<div class="gmail_quote">Hey I'm using the Nagios check_ping utility version v1810 (nagios-plugins 1.4.11) and I think I have a DNS resolution problem. check_ping can't resolve a host correctly and reports a network problem. This is the default command line: [root@machine libexec]# ./check_ping -H domain.tld -w 3000.0,80% -c 5000.0,100% -p 5 CRITICAL - Network Unreachable (domain.tld) However, there is no apparent resolving problem: [root@machine libexec]# host domain.tld<a href="http://intersphere.info" target="_blank"></a> <a href="http://intersphere.info" target="_blank">domain.tld</a> has address <a href="http://69.46.229.12" target="_blank">xx.xx.xxx.12</a> <a href="http://intersphere.info" target="_blank">domain.tld</a> has IPv6 address ::ffff:<a href="http://69.46.229.12" target="_blank">xx.xx.xxx.12</a> <a href="http://intersphere.info" target="_blank">domain.tld</a> mail is handled by 10 <a href="http://mx1.emailsrvr.com" target="_blank">mx1.emailservice.com</a>. <a href="http://intersphere.info" target="_blank">domain.tld</a> mail is handled by 20 <a href="http://mx2.emailsrvr.com" target="_blank">mx2.emailservice.com</a>. I've read the help for check_ping, and it states: This plugin uses the ping command to probe the specified host for packet loss (percentage) and round trip average (milliseconds). It can produce HTML output linking to a traceroute CGI contributed by Ian Cass. The CGI can be found in the contrib area of the downloads section at <a href="http://www.nagios.org/" target="_blank">http://www.nagios.org/</a> However, the ping command itself doesn't seem to have any problems (resolving, reaching): [root@machine libexec]# ping -c 1 domain.tld PING domain.tld<a href="http://intersphere.info" target="_blank"></a> (xx<a href="http://69.46.229.12" target="_blank">.xx.xxx.12</a>) 56(84) bytes of data. 64 bytes from <a href="http://dndc-web2.dndchosting.com" target="_blank">ptr.hostingcompany.com</a> (<a href="http://69.46.229.12" target="_blank">xx.xx.xxx.12</a>): icmp_seq=1 ttl=52 time=57.0 ms --- domain.tld<a href="http://intersphere.info" target="_blank"></a> ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 57.074/57.074/57.074/0.000 ms Ping version: [root@machine ~]# ping -V ping utility, iputils-ss020927 Is there anything I'm missing? This problem occurs with only one specific host out of rather large number, so I'm really at a loss with conclusions on this. Thanks, Yaron. </div>