title: What are proper status codes for CORS preflight requests?
body: <p>What status code should a well-written HTTP server return when it gets a CORS preflight (<code>OPTIONS</code>) request?</p>
  
  <p><code>200</code>, <code>204</code> or something else?</p>
  
  <p>Should the status code be different in case origin is allowed (and corresponding headers will be set) or not allowed (and CORS headers will not be set or will not match the origin)?</p>