Currently my ISP Digi Spain configures a DNS Server with IPv6 that is not able to resolve my web mounted on an IIS, from an Azure virtual machine.

The virtual machine is assigned a public IPv4, which we have configured with our SSL certificate and defined in our DNS. But, for some unknown reason the DNS server of my ISP is not able to resolve.

Regardless of whether I can solve the problem with the ISP, by configuring other DNS servers I do not understand why if I resolve the majority of websites and the one I have mounted on my IIS running in the Azure virtual machine does not.

Please, I need to know if there is any configuration at subscription level or in my IIS that allows the resolution of the web.

Thank you! Javier C.