Static packet filtering leaves all ports open for RealAudio all the time, but dynamic packet filtering opens the necessary ports when the request is made and closes them when the connection is terminated. Proxy Server is named after one of its strongest features. Like BorderManager, Proxy Server provides Web, hierarchical, and reverse caching. But unlike BorderManager, Proxy Server uses its own protocol, CARP, for hierarchical caching. Like ICP, CARP lets you connect multiple proxy servers so they can share their cache information.
CARP can perform distributed caching or intelligent load balancing among the servers.
For example, you can configure a proxy server running on fast hardware to handle more of the cache requests than a slower server. We used the feature to distribute the load evenly among PCs running Proxy Server. Another of Proxy Server's features that BorderManager lacks is the server proxy function for reverse proxying. Security is provided using Windows NT RAS user names and passwords. We have to give BorderManager bonus points in this area.