This is a parametric bash script that you can set up to run at startup or as a cron job in each one of your server.
Each time the server will boot up or execute the script an automatic API call will be created to create if not existent, or update if necessary the related DNS record hosted on Rackspace Cloud.
Please refer to:
http://docs.rackspace.com/cdns/api/v1.0/cdns-devguide/content/index.html
An easy script for updating your Dynamic DNS records at SiteLutions.com written in Bash. You may update several dynamic DNS accounts, just add one conf-file for each account
XMDNS is an extensible DNS management scheme that uses XML to store data. It features easy manipulation of views (or split horizon DNS). There is also support for hand-crafting records for situations where complicated rules must be enforced.