If you want to test if DNSSEC is correctly implemented for a domain, a great tool is the “DNSSEC Analyzer” operated by Verisign Labs:
You simply enter the domain name to be tested into the form and the free service will go to work:
Here is an example of what a successful verification of DNSSEC functionality should look like (click on the image to see the actual results):
A nice feature of the service is that the URL reflects the site name you are testing (ex. http://dnssec-debugger.verisignlabs.com/www.internetsociety.org) which means that you can easily bookmark that URL to easily try it again if you are in the midst of debugging your DNSSEC configuration.