What is the default HTTP version of WebClientProtocol for .Net 4.5.1

Right now my program is trying to make a remote call to a SOAP web service. The way we called:

WebClientProtocol clientProtocol = new WebClientProtocol ;
...........
...........Specify attributes of clientProtocol............;
...........
method.Invoke(clientProtocol , parameters);

      

        
        
        
      

    

However, I am unable to specify the HTTP protocol version for the WebClientProtocol. I wonder if there is a way to specify?

and I'm also wondering how the .NET Framework decides which version of HTTP to use? Is HTTP 1.1 the default? or does it automatically detect which version of HTTP the remote server is using and is configured for that version of HTTP?