I have a LAN (with ip range 5.2.2.1 - 5.2.2.255). In the LAN there is a RedHat9 server which contains a name server (bind 9.2.1). The LAN is connected to the internet through the RedHat machine. So the RedHat machine has two NIC. The ip address of a NIC is 5.2.2.1 (this is inside the LAN). The other NIC has a public ip address: 212.200.122.xxx (this take place outside the LAN). I want to register a domain but it need a DNS configuration in the RedHat machine. My question is:
Should I make zone "in-addr.arpa.122.200.212" too, or only the zones:
in-addr.arpa.2.2.5
mydomain
local
in-addr.arpa.0.0.127

You can make a arpa zone for your Public IP as well as your Private IPs, a good practice.
The PTR record xxx.122.200.212.in-addr.arpa query will however be resolved by your ISP DNS.

Thank You!