This is stolen from MS, I'm feeling lazy.....
How to Create a Reverse Lookup Zone:
Start the DNS snap-in. To do this, click Start, point to Programs, point to Administrative Tools, and then click DNS.
Under DNS, expand Host name (where Host name is the host name of the DNS server).
Expand Reverse Lookup Zones.
Right-click Reverse Lookup Zones, and then click New Zone. The New Zone Wizard starts. Click Next to continue.
Click Standard primary, and then click Next.
In the Network ID box, type the network ID. For example, type 192.168.0, and then click Next.
NOTE: The network ID is that portion of the TCP/IP address that pertains to the network. For additional information about TCP/IP networks, click the article number below to view the article in the Microsoft Knowledge Base:
Q164015 Understanding TCP/IP Addressing and Subnetting Basics
On the Zone File page, click Next, and then click Finish.
The new zone is listed under Reverse Lookup Zones in the DNS tree.
How to Modify the Reverse Lookup Zone Properties:
To modify or verify the zone properties:
Start the DNS snap-in. To do this, click Start, point to Programs, point to Administrative Tools, and then click DNS.
Under DNS, expand Host name (where Host name is the host name of the DNS server).
Expand Reverse Lookup Zones.
Under Reverse Lookup Zones, right-click the zone that you want (for example, 102.168.0.x Subnet), and then click Properties.
In the Allow dynamic updates list, click Yes.
Click the Start of Authority (SOA) tab.
In the Responsible person box, type the e-mail address that you want (in the format of "username.domain.com"

. For example, if the e-mail address is support@ example.com, type support. example.com.
Click Apply, and then click OK.
NOTE: When you create the forward and reverse lookup zones, the DNS service automatically creates an "A" record for the DNS server. However, it does not create a PTR, or reverse lookup record, for the DNS server.
To create a PTR record for the DNS server:
Right-click the reverse lookup zone (for example, 192.168.0.x Subnet), and then click New Pointer.
In the Host IP number box, type the host portion of the DNS server IP address. For example, if the DNS server is on a "C" class network and has an IP address of 192.168.0.10, the host portion of the IP address is 10. In this case, type 10.
In the Host name box, type the host name of the DNS server. For example, type dnsserv. example.com.
Click OK.