title: Strange issue with CORS preflight request fails on IE 11
body: <p>The problem, is that the the POST query fails on IE11, in all the other browsers it's seems working.</p>
  
  <p>Lets describe the problem step by step:</p>
  
  <ol>
  <li>XHR request from application to REST API.</li>
  <li>Preflight OPTIONS request (request parameters are following)</li>
  </ol>
  
  <blockquote>
  <pre><code>Accept:                         */*
  Origin:                         https://app.example.com
  Access-Control-Request-Method:  POST
  Access-Control-Request-Headers  content-type, accept
  :                               
  Accept-Encoding:                gzip, deflate
  User-Agent:                     Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko
  Host:                           api.example.com
  Content-Length:                 0
  Connection:                     Keep-Alive
  Cache-Control:                  no-cache
  </code></pre>
  </blockquote>
  
  <ol start="2">
  <li>preflight request response parameters are:</li>
  </ol>
  
  <blockquote>
  <pre><code>X-Powered-By:                   Sugar
  Access-Control-Allow-Origin:    https://app.example.com
  Vary:                           Origin
  Access-Control-Allow-Credentia  true
  ls:                             
  Access-Control-Allow-Methods:   GET,POST,DELETE,OPTIONS
  Access-Control-Allow-Headers:   X-Requested-With,X-HTTP-Method-Override,Content-Type,Accept
  set-cookie:                     sugar.sid=s%Pb9OoTTPUkVw%2F2vUPoFMNG
                                  LMXACSkQevo; Path=/; Expires=Thu, 15 Jan 2015 18:27:07 GMT; HttpOnly; Secure
  Date:                           Mon, 12 Jan 2015 18:27:07 GMT
  Connection:                     close
  </code></pre>
  </blockquote>
  
  <ol start="3">
  <li>The real HTTP request after preflight request parameters:</li>
  </ol>
  
  <blockquote>
  <pre><code>Accept:           application/json
  Content-Type:     application/json
  Referer:          https://app.example.com/
  Accept-Language:  en-US
  Origin:           https://app.example.com
  Accept-Encoding:  gzip, deflate
  User-Agent:       Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko
  Host:             api.example.com
  Content-Length:   9
  Connection:       Keep-Alive
  Cache-Control:    no-cache
  Cookie:           sugar.sid=s%3A-%2FGF1YoFmRfmBsxK4vLBoGjY5NT0QoYvf5s;
  </code></pre>
  </blockquote>
  
  <ol start="4">
  <li>Last response parameters:</li>
  </ol>
  
  <blockquote>
  <pre><code>Content-Type:    application/json; charset=utf-8
  Content-Length:  72
  Vary:            Accept-Encoding
  Date:            Mon, 12 Jan 2015 18:27:07 GMT
  Connection:      close
  </code></pre>
  </blockquote>
  
  <ol start="5">
  <li>Basically the response end with the IE error:  Origin: <a href="https://app.example.com" rel="nofollow">https://app.example.com</a> not found in Access-Control-Allow-Origin header. Does the first request needs also the Access-**-Origin header, which seems to be missing.</li>
  </ol>
  
  <p>Also followed the CORS flow chart for debugging problem, but I could not spot it <a href="http://www.html5rocks.com/static/images/cors_server_flowchart.png" rel="nofollow">http://www.html5rocks.com/static/images/cors_server_flowchart.png</a>.</p>
  
  <p>I am using Node.js Express server with the node-cors module + modified options.</p>