Nor do they like updating schannel.dll (the underling SSL&#x2F;TLS stack) unless there&#x27;s an extremely serious vulnerability in it. And even then, they bungle it more often than not (<a href="http:&#x2F;&#x2F;www.infoworld.com&#x2F;article&#x2F;2848574&#x2F;operating-systems&#x2F;microsoft-botches-kb-2992611-schannel-patch-tls-alert-code-40-slow-sql-server-block-iis-sites.html" rel="nofollow">http:&#x2F;&#x2F;www.infoworld.com&#x2F;article&#x2F;2848574&#x2F;operating-systems&#x2F;m...</a>).<p>The reason SChannel matters is that the protocol used to negotiate which &quot;next generation&quot; protocol is to be used for the HTTP connection (not session, minor point) is something called Application-Layer Protocol Negotiation. ALPN is a TLS extension sent as part of the ClientHello but wasn&#x27;t added to SChannel until Windows 8.1&#x2F;2012 R2 Server. (There was a predecessor to ALPN called NPN that Adam Langley authored&#x2F;implemented for Chrome but Microsoft never implemented it.)