def reverse_domain_from_network(ip_network):
    """Create reverse DNS zone name from network address (ipaddress.IPv4Network)"""
    prefixlen = ip_network.prefixlen

    if prefixlen % 8:
        return ip_network.reverse_pointer  # classless
    else:
        return ip_network.network_address.reverse_pointer[(4 - (prefixlen / 8)) * 2:]