title: Underscore in subdomain label.. valid or not?
body: <p>Django URLValidator will raise a validation error for this website URL because of the underscore:</p>
  
  <p><a href="http://beauharnois_bupa.tripod.com/" rel="nofollow">http://beauharnois_bupa.tripod.com/</a></p>
  
  <p>From what I've read some says that it's not a valid domain name, some say it is and the RFCs seems to say that it's legal in the subdomain label but not in the hostname.</p>
  
  <p>My guess is that it is legal in the subdomain label since the website mentioned above works..</p>
  
  <p>Who's right ?</p>