Our LAN has the address range 172.16.20.0/22 giving us possible addresses
from 172.16.20.1 - 172.16.23.254

When creating ARPA zones for this do I need to create one zone
(16.172.IN-ADDR-ARPA) or 4 separate zones (20.16.172, 21.16.172 etc).

Thanks

Paul Gregory