External IP DNS query and server
Enter two space-separated values: the DNS query name followed by the nameserver. For example: myip.opendns.com resolver1.opendns.com.

Virtualmin uses dig to request an A record for IPv4 or an AAAA record for IPv6 from the specified nameserver. If this field is set to No, dig is unavailable, or the query fails, Virtualmin uses the configured HTTP detection service instead.

When the system is behind NAT, a proxy, or a VPN, the result is the public address of that gateway or endpoint rather than an address assigned directly to the system.