B. Anonymous access. A firewall sits between your network and the Internet. Your Exchange server has its name and IP address entered into a public DNS server on the Internet. Your network's firewall prohibits traffic on all ports that are not explicitly allowed. Management would like users to be able to connect over the Internet to your Exchange server using Microsoft Outlook and LDAP applications.
Policy dictates that passwords be transmitted in a secure manner.
POP3 clients could connect to the Exchange server and download their messages. Assign port numbers to the Exchange Directory Service and Information Store. Then allow those ports through the firewall. Configure LDAP on the Exchange server to allow anonymous access. Configure the Exchange protocols to use SSL as an authentication method.