But my first guess would be that you are leaving the nameserver field blank, have entered an IP that is not a nameserver, entered an invalid IP or entered a FQDN rather than an IP for your nameserver.
You could try setting google's public DNS (8.8.8.8) and see what happens...
Beyond that, without more info of your config, environment, etc it's hard to offer many more suggestions...
Probably need more details to give meaningful answer...
But my first guess would be that you are leaving the nameserver field blank, have entered an IP that is not a nameserver, entered an invalid IP or entered a FQDN rather than an IP for your nameserver.
You could try setting google's public DNS (8.8.8.8) and see what happens...
Beyond that, without more info of your config, environment, etc it's hard to offer many more suggestions...