title: X-P2P-PeerDist header: where does it come from?
body: <p>I'm seeing this HTTP header on some requests made to my server:</p>
  
  <pre><code>X-P2P-PeerDist: Version=1.0
  </code></pre>
  
  <p>I'm aware of this: <a href="http://www.faqs.org/patents/app/20110016220#ixzz3g3X8lSYF" rel="nofollow noreferrer">http://www.faqs.org/patents/app/20110016220#ixzz3g3X8lSYF</a>, but I would like to know what are the known clients sending that header.</p>
  
  <p>Any idea?</p>
  
  <p>UPDATE: as requested, i'm including the other headers sent with the request (I've obfuscated some private stuff that are related to our customer with ***):</p>
  
  <pre><code>GET http://***.com/ HTTP/1.1
  Accept: application/x-ms-application, image/jpeg, application/xaml+xml, image/gif, image/pjpeg, application/x-ms-xbap, */*
  Connection: Keep-Alive
  Accept-Language: en-US
  User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; Win64; x64; Trident/7.0; .NET CLR 2.0.50727; SLCC2; .NET CLR 3.5.30729; .NET CLR 3.0.30729; InfoPath.3; .NET4.0C; .NET4.0E)
  X-P2P-PeerDist: Version=1.0
  UA-CPU: AMD64
  Accept-Encoding: gzip, deflate, peerdist
  Host: ***.com
  Cookie: SMSESSION=***; OrgName=***; authCookie=***; ASP.NET_SessionId=***
  Pragma: no-cache
  Cache-Control: no-cache
  </code></pre>
  
  <p>The user agent seems to indicate IE11 (<code>Trident/</code>) in IE7 mode (<code>compatible; MSIE 7.0</code>), but I'm not getting the X-P2P-PeerDist header when I'm using this config, so I don't think it's directly related.</p>