I have ddclient working with zonedit on 10 domains perfectly. If you need assistance with that, let me know.
DDClient:
http://ddclient.sourceforge.net
ZoneEdit:
http://www.zoneedit.com
Common Open Ports taken from ctroyp's post but edited
Code:
Port 21 (tcp) is open (ftp)!
Port 22 (tcp) is open (ssh)! <-- Caution!
Port 25 (tcp) is open (smtp)!
Port 80 (tcp) is open (http)!
Port 81 (tcp) is open (ISPConfig)!
Port 110 (tcp) is open (pop3)!
Port 443 (tcp) is open (https)!