def _resolves_to_ipv6(host: str) -> bool:
    """Returns True if the system resolves host to an IPv6 address by default."""
    resolves_to_ipv6 = False
    try:
        for res in socket.getaddrinfo(host, None, socket.AF_UNSPEC):
            af, _, _, _, _ = res
            if af == socket.AF_INET6:
                resolves_to_ipv6 = True
    except socket.gaierror:
        pass

    return resolves_to_ipv6
Returns True if the system resolves host to an IPv6 address by default.
dummyserver/socketserver.py