Tunneling can be an important backup for QlikView Server communications; if port 4747 is blocked for any reason (on either the server or the client machine), tunneling over port 80 will be the only way your users can access their applications. Most people who have tried to implement tunneling with QVS 9 or 10 running IIS have probably noticed a problem immediately: when you enter the URL to test tunneling (http://localhost/scripts/qvstunnel.dll?testtunnel) IIS does not use QVTunnel.dll to implement the tunneling protocol, but rather presents you with a prompt to download the DLL. Fortunately, there is a simple fix for this.
%windir%system32inetsrvappcmd.exe set config "Default Web Site/Scripts/QvsTunnel.dll" "/commit:Default Web Site/Scripts" /section:handlers /accessPolicy:Read,Script,Execute
Applied configuration changes to section "system.webServer/handlers" for "MACHINE/WEBROOT/APPHOST/Default Web Site/Scripts/QvsTunnel.dll" at configuration commit path "MACHINE/WEBROOT/APPHOST/Default Web Site/Scripts"