Passive FTP

Hi
My IP is dinamic, so when my ip change, i cant connect to my FTP server, because the option "Respond with external IP for passive FTP request" only accept IP, not my dyndns hostname.
When i was using Fillezilla server on my computer, i was using my dyndns domain.
Whats the possibility to use dyndns or auto update the new ISP IP adress?
Sorry my english :s
ty
My IP is dinamic, so when my ip change, i cant connect to my FTP server, because the option "Respond with external IP for passive FTP request" only accept IP, not my dyndns hostname.
When i was using Fillezilla server on my computer, i was using my dyndns domain.
Whats the possibility to use dyndns or auto update the new ISP IP adress?
Sorry my english :s
ty