title: Reverse IP lookup with PHP
body: <p>In PHP is there a function to do a reverse lookup on a domain name to find out how many websites are hosted on the particular shared hosting server that domain name is hosted on. Or, a way to do this with PHP?</p>
  
  <p>Now, I'm already aware of the online services that offer this. However, I want to write a script to do it myself. I just can't figure it out.</p>
  
  <p>Any suggestions that are not suggesting the use of a 3rd party service would be great.</p>