Below is Kb article 323445, showing how to create Reverse DNS zone and Forward DNS zone, Forward DNS zone is the traditional zone
Name to 32 Bits IP address resolution and we call records in forward lookup zone, host records. Reverse DNS zone is created in special way, it gets created against a SUBNET. The job of Subnet mask, is the define IP address into two distinct part, Network Portion and host portion.
We call records in Reverse DNS zone PTR records (pointer records), 32 Bits IP address resolves to human friendly names. The IP address is 32 bits Binary number and so does the Subnet Mask.
IP=Net ID + Host ID and the SM defines or determines what portion of an IP is belong to a Network, what portion is belong to a host. This might not seem so important at the first look, however, this mechanism does a critical role in TCP/IP network and makes network complete, and without Subnet Mask IP address is useless. Just like eating a French fries without ketchup, because without ketchup, fries won't know where to go to.
How to Create a Reverse Lookup Zone
How to Create a Forward Lookup Zone
To create a new forward lookup zone: