Although it doesn't take full advantage of all ISA Server 2004 has to offer, the deployment scenario of an ISA Server in the DMZ of an existing firewall is very common, and can be a useful component of a broad security strategy. ISA Server 2004 is a relatively cost-effective approach to maximizing the security of edge-facing web services. This includes common attack targets such as Outlook Web Access servers, SharePoint sites, and any other websites.
ISA Server 2004 contains preconfigured and intelligent rules that allow for the configuration of reverse proxy capabilities that scan, filter, and reprocess the traffic sent to web servers, allowing for intelligent web filtering in addition to hard-to-find capabilities such as end-to-end SSL processing. For those organizations that are not in a position to restructure their existing security configuration, these capabilities provide them with an impressive additional layer of security without making any fundamental changes to their environment.