Nagios web interface not matching with some command line checks

punt · 09-12-2015, 09:34 PM

This is the second time this has happened (but with another check) so I'm going to post here.

I just changed the DNS of one of my servers. I have a check_dns command that runs and that is failing on the web interface ONLY, but it's working fine on the command line interface.

The command is simple, just the same thing I run on the web interface:

Code:

define service{
        use                             local-service
        host_name                       theserver
        service_description             DNS
        check_command                   check_dns
        notifications_enabled           1
        }

If I run check_dns on the CLI, I get:

Code:

# ./check_dns theserver
DNS OK: 0.027 seconds response time. theserver returns the.right.ip.address|time=0.026892s;;;0.000000

But on the web interface, the same IP address fails:

Code:

Domain the.same.ip.address was not found by the server

Also, it's defined properly in the .cfg file:

Code:

define host{
        use                     linux-server            ; Name of host template to use
        host_name               theserver
        alias                   theserver.com
        address                 the.same.ipv4.address.as.before
        contact_groups          admins
        notification_period     24x7            ; Send notification out at any time - day or night
        }

Why would this be? I feel like it will "catch up" hours later but I'm running the same check! This is not making any sense to me.

punt · 09-13-2015, 07:41 AM

Hasn't caught up yet! Anyone have any ideas why this is happening? Am I missing something?

punt · 09-13-2015, 08:04 AM

This is also really strange. I finally can reproduce the error I am seeing on the command line.

Code:

# ./check_dns -H the.ip.address
Domain the.ip.address was not found by the server

But I am trying to do the DNS lookup and it's correct!

Code:

# host theserver.com
theserver.com has address the.ip.address
theserver.com mail is handled by 0 theserver.com

Wut?!

punt · 09-13-2015, 08:12 AM

Okay, I keep responding to myself so I can help other people. I think I just need to get a PTR record. Here's hoping it set up and fixes the issue.

Habitual · 09-13-2015, 08:19 AM

Poor Man's DNS?

Code:

vi /etc/hosts

and add

Code:

the.ip.address theserver.com

MadeInGermany · 09-19-2015, 02:03 AM

Do you have nscd running? Then reduce positive host caching time to a little over your usual check interval.
On the command line you should check with

Code:

getent hosts <ip or hostname>