Dynamic DNS in Cisco IOS
September 25, 2009
Dynamic DNS support was introduced in IOS version 12.3(8)YA. I recently started using this service with my DynDNS account and thought it might be useful to provide a short tutorial for myself and others to refer back to. It goes without saying that you will need an active DynDNS membership for this to work.
Begin by logging into your router via SSH, telnet, management console or what have you. Go into enable mode and proceed to the global configuration (conf t).
Enable the DDNS service:
ip ddns update method ddns
You will then be in the DDNS configuration. Enter the following statements, replacing the obvious variables with your own information. Be sure to press Ctrl-V prior to typing ? in the command line. If you don't, you will be prompted with IOS context-sensitive help information.
HTTP add http://USER:PASS@members.dyndns.org/nic/update?system=dyndns&hostname=HOST&myip=<a> interval maximum 1 0 0 0
When you are finished, exit out of the DDNS configuration and go into the WAN interfaces configuration (int <interface>). Enter the following:
ip ddns update ddns
And there you have it. The router should now automatically update your DynDNS host when needed. Don't forget to save your changes (wr).