I currently have my Cisco ASA 5505 firewall configured to forward port 80 from the outside interface to a host on my dmz interface. I also need to allow clients on my inside interface to access the host in the dmz by entering the public ip / dns record in their browsers. I was able to do that by following the instructions here, resulting in the following configuration:

static (dmz,outside) tcp interface www 192.168.1.5 www netmask 255.255.255.255 
static (dmz,inside) tcp 74.125.45.100 www 192.168.1.5 www netmask 255.255.255.255

(Where 74.125.45.100 is my public IP and 192.168.1.5 is the IP of the dmz host)

This works great except for the fact that my network has a dynamic public IP and this configuration will therefore break as soon as my public IP changes. Is there a way to do what I want with a dynamic ip?

Note: Adding an internal DNS record won't solve my problem since I have multiple dmz hosts mapped to different ports on the public IP.