Nagios Support Forum

Dear Expert

In /etc/resolv.conf , we have 3 DNS, one of DNS was having issue, due to this issue, nearly all HOSTs giving error : "Plugin timed out after 10 seconds".
We removed (disabled) that DNS (10.20.30.40) from this /etc/resolv.conf file and issue got fixed.

FYI, we are not fully depend on this DNS server (10.20.30.40) to resolve the HOSTs. We rely on our localhost DNS (/etc/hosts file), so how to prioritize localhost DNS (/etc/hosts) file to be our Prime DNS to resolve Nagios HOSTs? You know it will never fail.

Regards

The file that controls the order in which lookups are done is this file. The option that controls the order of the look ups is the hosts: option.
If the option is set like below, it should look in the hosts file first and if it cannot find the host, it will do a DNS lookup. Fore more details, you can look at the MAN page.
http://man7.org/linux/man-pages/man5/ns ... onf.5.html

Dear tgriep

We checked and found the setting is same what you suggest/recommended. Its already there, even though why the plugin time out alert generated?

more /etc/nsswitch.conf | grep hosts
#hosts: db files nisplus nis dns
hosts: files dns

Regards

This is more of a general Linux/networking question than a Nagios question. As far as I know we don't touch anything related to DNS on install or upgrade. You would do best to find a network admin to look into this issue, as it is somewhat out of scope for what we support.