Your network contains a Web server named Server1 that runs Windows Server 2003 and Internet Information Server （IIS）. Server1 has a server certificate from an Enterprise Certificate Authority （CA） installed.External users report that when they try to access the Web site from outside the corporate network by using a Web browser， they receive the following warning message： “There is a problem with this Web site’s security certificate. The security certificate presented by this Web site was not issued by a trusted certificate authority.”  You find that users on the corporate network do not receive this error. You need to ensure that external users do not receive the warning message when connecting to Server1.  What should you do？（）

• A、In IIS Manager， enable the Enable client certificate mapping option.
• B、In IIS Manager， replace the certificate with a certificate obtained from a public Certification Authority.
• C、In Local Security Policy， enable Domain Member： Require strong （Windows 2000 or later） session key.
• D、In Local Security Policy， enable Domain Member： Digitally encrypt or sign secure channel data （always）.