How to Make a /22 Reverse Zone in Bind? (255.255.252.0))
Solution 1:
With the scheme defined for mapping IPv4 addresses to reverse DNS names, namely 192.0.2.17 becomes 17.0.2.192.in-addr.arpa, it's impossible to do delegations that are not at the /8, /16 or /24 boundaries (or for a single address, /32 if you will).
For larger than /24 networks, you'd simply delegate multiple zones of the closest smaller size.
For instance a /22 network would be four consecutive /24 zones.
Eg 10.7.56.0/22 would be 56.7.10.in-addr.arpa + 57.7.10.in-addr.arpa + 58.7.10.in-addr.arpa + 59.7.10.in-addr.arpa.
For smaller than `/24` networks, a bit of a clever hack (defined in [rfc2317](https://www.rfc-editor.org/rfc/rfc2317)) is used, where in the parent zone `CNAME` records are added for the names belonging to each individual IP address of the smaller network, pointing all of these into a new namespace and then delegating that namespace instead.