Do I have to create a PTR record?

HW:Cisco Pix Firewall
OS:Win2k
I have mapped DMZ addys for internal servers. IIS sits on the DMZ. I cannot ping inside from the DMZ. Do I have to create PTR records for the dmz addresses on the inside DNS server or on the dmz dns server? Dynamic asp’s on the IIS box requests real time data on the inside app server. Since IIS can’t see inside I cannot get IIS to recognize the app server name & get the dynamic data it needs to display on the asp.