Make sure the hostname is valid, whereby the hostname will resolve to an IP address which is your server IP address. Therefore create an A record for a domain/subdomain eg. ns1.server.com point to server IP address.
1.) Log into DirectAdmin control panel using admin credential. Go into the “Administrator Settings” page as shown in picture below:
2.) On the “Administrator Settings” page, scroll down to the “server settings” category and look for “Server’s Hostname”. Here is where you change your server DirectAdmin’s hostname.
3.) After insert the new hostname, scroll down to the bottom and search for “Save” button. Click on save and DirectAdmin will save and proceed with the changes.