title: user agent string is Mozilla/4.0 (compatible; MSIE 7.0) when compatibility mode is off
body: <p>some clients reported that our website do not work in IE11.
  we don't have access to their computer, so we asked for screenshot and we dig into our logs.</p>
  
  <p>and found those clients' browsers sent the following agent string:
  Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.3; WOW64; Trident/7.0; .NET4.0E; .NET4.0C; .NET CLR 3.5.30729; .NET CLR 2.0.50727; .NET CLR 3.0.30729; CPNTDFJS; McAfee; GWX:QUALIFIED)"},</p>
  
  <p>and from the screenshot, we can see our site layout is broken. 
  so we come to a conclusion that those clients are using compatibility mode in IE11.</p>
  
  <p>however, the clients checked and said they don't have compatibility mode enable, enterprise mode is not enabled either.</p>
  
  <p>since we don't have access to clients computer, so would like to get idea from you guys and see if anyone know what else we should check or why this happens?</p>
  
  <ol>
  <li><p>only some clients are having this issue. and we could not reproduce it on our computer.</p></li>
  <li><p>currently on our website, we dont have  set in page head, because we thought IE11 would be smart enough to use Edge as default.</p></li>
  <li><p>Clients said compatibility mode or enterprise mode is off. Could it be a cache or something else that is not visible on the surface?</p></li>
  </ol>
  
  <p>really out of idea, please shed some lights. Thanks!</p>