I have configured my DDNS on my cisco router. But no update happens. Here is the config file ;

ip domain lookup source-interface Dialer0
ip name-server 8.8.8.8
ip name-server 212.252.114.8
ip name-server 4.2.2.1
ip name-server 8.8.4.4
ip ddns update method dynu
HTTP
add http://api.dynu.com/nic/update?hostname=******.dynu.net&password=S**********
interval maximum 0 0 5 0
!

Can you share the log? One common mistake is not passing in the '?' in the update URL:

To insert the special character ? in the IP update URL, first, you need to use the combination of Ctrl+v and then Shift+?.