import ipaddress

def reverse_zone(network):
    """Reverse a network zone"""

    if network.version == 4:
        boundary = 8  # break to the byte
    elif network.version == 6:
        boundary = 4  # break to the nimble

    assert network.prefixlen % boundary == 0
    length = (network.prefixlen // boundary)

    full_network_reverse = network.network_address.reverse_pointer

    splitted = full_network_reverse.split(".")
    splitting_len = int(network.max_prefixlen / boundary)
    splitted = splitted[splitting_len - length:]

    reversed_zone = ".".join(splitted)

    return reversed_zone


net1 = ipaddress.IPv4Network("10.128.12.0/24")
net2 = ipaddress.IPv4Network("10.129.0.0/16")
net3 = ipaddress.IPv4Network("10.0.0.0/8")

net4 = ipaddress.IPv6Network("2001:470:142:3::/64")
net5 = ipaddress.IPv6Network("2001:470:142::/48")
net6 = ipaddress.IPv6Network("2a09:6840::/32")

#>>> reverse_zone(net1)
#'12.128.10.in-addr.arpa'
#>>> reverse_zone(net2)
#'129.10.in-addr.arpa'
#>>> reverse_zone(net3)
#'10.in-addr.arpa'
#>>> reverse_zone(net4)
#'3.0.0.0.2.4.1.0.0.7.4.0.1.0.0.2.ip6.arpa'
#>>> reverse_zone(net5)
#'2.4.1.0.0.7.4.0.1.0.0.2.ip6.arpa'
#>>> reverse_zone(net6)
#'0.4.8.6.9.0.a.2.ip6.arpa'