I have a problem with error generated on https://intodns.com for domain configured in ISP. All works well except, probably, allow transwer. Intodns gives error: Code: ERROR: One or more of your nameservers did not respond: The ones that did not respond are: X.X.X.X X.X.X.X is IP address of secondary dns for configured domain. In ISP -> DNS -> DNS Zone -> Allow zone transfers to these IPs (comma separated list) - I put IP X.X.X.X. Should something more be configured on server with IP X.X.X.X? Of course server with X.X.X.X is responding on ping and works well for domain configured on itself.