Cisco’s IOS never ceases to amaze me.   While this feature has been around for a bit (since12.3) and I was aware of it, I only just recently decided to give it some attention.   If you want to host a web-server or other publicly   accessible network resource and don’t have a static IP address, Dynamic Domain Name Server (DDNS) is for you.   Services like DynDNS give you the ability to automagically update the dynamically assigned IP address from your ISP with the domain name you own.   There are several ways to do this including manually updating the IP address yourself or using a software client from within your network.   Another option is to use IOS’s DDNS support.   Below is a simple example of how to configure it on IOS routers:

Router#config t
Router(config)#ip ddns update method test
Router(DDNS-update-method)#HTTP
Router(DDNS-HTTP)#add http://user:pass@update.someddnsservice.org/index.php?ver=0.1&domain=yourdomain.com
Router(DDNS-HTTP)#exit
Router(DDNS-update-method)#interval maximum 0 2 0 0
Router(DDNS-update-method)#interval minimum 0 1 0 0
Router(DDNS-update-method)#exit
Router(config)#interface fast0
Router(config-if)#ip ddns update test
Router(config-if)#end
Router#copy run start
Router#

Pretty simple, eh?   There is a lot more you can do with this feature which includes updating a list of hosts from within your network.   If you want to know more, or what each command means, feel free to leave a comment or check out Cisco’s website.   Lastly, remember that the url string is not encrypted in the example above which means your username and password is visible to those who are trying to find it.   Other than that, enjoy!

-Tim