You are the network administrator for The network consists of a single Active Directory domain named All servers run Windows Server 2003. All client computers run Windows XP Professional. You install Software Update Services (SUS) on a network server named Testking1. When you attempt to synchronize Testking1 with the Windows Update servers, you receive an error message. You suspect that your proxy server requires authentication. You open Internet Explorer and verify that you can communicate with an external Web site by using the proxy server. You need to ensure that Testking1 can communicate with the Windows Update servers. What should you do on Testking1?（）