In an enabled user and configure terminal mode enter the below edited details. ip ddns update method dyndns HTTP add http://username:pa55w0rd@members.dyndns.org/nic/update?system=dyndns&hostname=<h>&myip=<a> interval maximum 28 0 0 0 ! interface Dialer0 ip ddns update hostname hostname.dyndns.org ip ddns update dyndns To enter a question mark you must type ctrl-v before pressing ? Use “debug ip ddns update” …