title: What is the correct HTTP Response to send in case of bad DNS Redirection?
body: <p>I've got a server hosting multiple websites. Server is written in Java+Jersey.
  If someone makes his DNS point to my service, but this DNS doesn't match any of my hosted websites, what should I answer? Note that I need to do this programmatically and can't rely on some customization of my Web container ( Tomcat ) .</p>
  
  <p>The problem is, if I display a « website not found » page, I shall have search engines reference my primary domain website under a false name, therefore downgrading its page rank because of someone else's mistake.</p>
  
  <p>I tried to change my /etc/hosts file to reproduce the behaviour but can't guess what other websites are doing in this case too.</p>
  
  <p>Any idea ? A simple 404 seems too light ? Bad Request seems inappropriate ...</p>