Cisco Routers and Dynamic DNS

Posted by Josh on Thu 19 Aug 2010
Categories: Cisco , Cisco Routers , Voice LAB - [12] Comments 

This short post demonstrates using ‘ip sla’ and  freedns.afraid.org for dynamic dns.

 

 

If you are not familiar with FreeDNS, it is simply a free / shared dns host. Individuals voluntarily host their domains on the FreeDNS servers and allow other users to create dns subdomains with their domain name.

 

 

Here are the steps

 

1. Create an account with the FreeDNS website

 

• Add a new subdomain
  1. Click the ‘Registry’ link
  2. Click on a domain you would like to link to…e.g. mooo.com
  3. Enter text in the subdomain field … e.g. blindhog

   

• Get the dynamic dns url
  1. Click the ‘Dynamic DNS’ link
  2. Right-Click on the ‘Direct URL’ link next to your new subdomain and select ‘Copy Link Location’
  3. Paste this link into notepad. We will use it later.

   

• Login to your cisco router and get into config mode.

 

• Configure  an ‘http get’ based sla monitorNote: Only enter the first part of the url (before the question mark) and do not hit enter. Press ‘ctrl+v’ then enter the second half of the url including the question mark. If you do not use ‘ctrl+v’ before the question mark will be used to display options of the ‘http get’ command.
  

  ip sla 1 http get http://freedns.afraid.org/dynamic/update.php?VEc..Or   ip sla monitor 1 type http operation get url http://freedns.afraid.org/dynamic/update.php?VEc..

   

   

   

• Create a new ip sla schedule to activate the update.
  

  ip sla schedule 1 lifetime forever start-time now Or  ip sla monitor schedule 1 life forever start-time now

• Use the following commands to troubleshoot
  

  show ip sla configuration show ip sla statistics debug ip sla trace debug ip sla error Or show ip sla monitor configuration show ip sla monitor statistics debug ip sla monitor trace debug ip sla monitor error