If you are getting this warning email:
Subject: [ipcheck] Problem with DNS setup on server.domain.com
This means your hostname (server.domain.com) cannot be resolved to an IP address.
Usually, this means that /etc/hosts is not set up correctly, and/or there is no DNS entry for server.domain.com
Make sure that /etc/hosts is configured correctly, and also that there exist a correct ‘A’ entry for the domain in the zone file.
This issue can also be caused by /etc/resolv.conf being setup incorrectly. Please check that file if you believe everything else is correct.
You may be able to automatically correct this problem by using the ‘Add an A entry for your hostname’ option under ‘DNS Functions’ in Web Host Manager.
You should know that this is not critical, however if you want to get rid of it you need to add A record to your DNS matching server hostname and pointed to your VPS IP, for example:
server.domain.com => 18.104.22.168