title: URL Shorten: how is this achieved?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1562367/how-do-short-urls-services-work">How do short URLs services work?</a>  </p>
  </blockquote>
  
  
  
  <p>I often see shortened urls from bitly.com such as <a href="http://bit.ly/abcd" rel="nofollow noreferrer">http://bit.ly/abcd</a>. How is this "bit.ly" realized at server side? Is it some DNS trick inside? </p>