Sadly, it's complicated. Read more here: http://blogs.msdn.com/b/ieinternals/archive/2013/09/21/internet-explorer-11-user-agent-string-ua-string-sniffing-compa

Sadly, it's complicated. Read more here: http://blogs.msdn.com/b/ieinternals/archive/2013/09/21/internet-explorer-11-user-agent-string-ua-string-sniffing-compatibility-with-gecko-webkit.aspx http://blogs.msdn.com/b/ieinternals/archive/2013/09/21/inter... But the default is: Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko