Every home consumer ADSL router I have come across uses a nice web gui interface where you can manage and configure your router settings from. These should hopefully be self explanatory to most of you. Most routers will also now come with DDNS support built into them. Again, this should also be self explanatory using the web gui interface.
The commands to configure a Cisco router through IOS to use DDNS however are not as well documented or self explanatory so I have pulled them from my running config using DynDNS as the service provider and pasted them below.
**You might find that it is necessary to hit the escape sequence Ctrl+v in order to enter the’?’ in the config url below otherwise the IOS parser will interpret the question mark as an attempt to invoke the context sensitive help.
In global config mode:
ip ddns update method update_name_blah
interval maximum 28 0 0 0
interval minimum 28 0 0 0
Then under the Dialer interface:
ip ddns update hostname example.dyndns.org
ip ddns update update_name_blah host example.dyndns.org
It is worth noting that your Cisco router will automatically update your DynDNS account every time your IP changes. If however you set your router update interval to update repeatedly and your IP address hasn’t changed there is a good chance your DynDNS account will be temporarily blocked, hence the reason I have set my manual update interval to every 28 days.