IPv4 DNS Reverse Zone generation

rev-zone.py

#! /usr/bin/env python3

import ipaddress

subnet = ipaddress.IPv4Network("192.168.0.0/22", strict=False)

if subnet.prefixlen > 24:
    raise ValueError("No Zone for subnets >/24")
elif subnet.prefixlen > 16:
    zone_length = 24
    split_length = 1
elif subnet.prefixlen > 8:
    zone_length = 16
    split_length = 2
else:
    zone_length = 8
    split_length = 3

prefix_diff = zone_length - subnet.prefixlen
if prefix_diff > 0:
    zone_subnets = subnet.subnets(zone_length - subnet.prefixlen)
else:
    zone_subnets = [subnet]

for subzone in zone_subnets:
    zone = list(reversed(str(subzone.network_address).split(".")))
    zone = ".".join(zone[split_length:]) + ".in-addr.arpa"
    print(zone)