title: sites down but server up, what to do?
body: <p>I could ping my websites but I got a 404 going there.
  My server was running normally, no new mail for root.</p>
  
  <ul>
  <li><p>Is there a service to alert you when your websites are down ?</p></li>
  <li><p>What do you usually do to understand why it's down?</p></li>
  </ul>
  
  <p>I took a look at the apache2/error.log and saw that it couldn't access one of the website I had deleted a few hours ago. I just did a a2dissite and restarted and it was fixed, I could access my websites.</p>
  
  <p>I either got lucky or I postponed a problem. Any idea what I should do next to make sure everything is alright? (I'm on debian by the way)</p>