You are employed as a system administrator at Certkiller.com. You decide to create an ASP.NETWeb application on the companies’ network. You do this using Microsoft .NET Framework v3.5.  You are in the process opf planning the establishing authentication for the Web application. Youneed to make sure that the application is able to support clients from untrusted domains. However，unknown clients should not be able to access the application.  What should you do？（）

• A、A
• B、B
• C、C
• D、D