title: Creating domain name checker
body: <p>I wonder how to make a domain name checker (testing for availability) for top-level domains?</p>
  
  <p>Eg. to check if the domain: stackoverflow.com or stackoverflow.dk is available or not. </p>
  
  <p>Do I need to be subscribed to a service to do this, or is there some simple magic behind such test?</p>
  
  <p>Thanks</p>