Despite all the changes, at its heart, IIS 6 is still just a platform for serving Web pages. IIS 6 will still provide static pages to clients who ask for them, and many other core features?such as the support for CGI and scripting technologies, ASP, FrontPage extensions, and so on?remain the same.

In fact, unless you want to take advantage of many of the new features provided in IIS 6, you can continue to use IIS in the same way you have before using the IIS 5 Isolation mode. This makes IIS 6 work in a 100% compatible way with IIS 5, and anything that runs currently within IIS 5 should work identically when IIS 6 is operating in this mode.

IIS 5 Isolation mode is probably the easiest way to make a migration from a Windows 2000 hosted IIS 5 Web site to Windows Server 2003 while you get used to the new features and optimize and tune a server for use in native IIS 6 mode.

For more information on making the migration from a previous version of IIS, see "Migrating from IIS 4/5 to IIS 6," (Chapter 7), p.119.

However, to make use of the new features, you will need to make some mental changes when working with the improved IIS snap-in for the Microsoft Management Console (MMC).

IIS 6 also includes a brand new Web-based interface for administration purposes, enabling you to monitor and manage your IIS installation even when MMC is not available.

Compatibility with most third-party filters, languages, and support tools is also retained. The ISAPI interface is still supported in IIS 6 and, in fact, includes a number of significant extensions, including the capability to 'chain' together ISAPI filters and to redirect requests from one URL to another location for processing.

However, it would be foolish not to take advantage of many of the new features, especially those specifically related to improving the stability and performance of your Web sites. If you are currently experiencing problems with crashed applications, hung services, and sometimes slow to respond servers, IIS 6 will eliminate many of the problems with few changes to your configuration.

For more information on compatibility and migrating from IIS 4 (Windows NT) or IIS 5 (Windows 2000), refer to "Migrating from IIS 4/5 to IIS6," (Chapter 7), p.119.

Interestingly, IIS 6 is also the first IIS revision that closely matches the execution model of Apache. Apache is the most popular Web-serving platform on any operating system, but a number of people are already considering moving to Windows Server 2003 to take advantage of some of the more advanced integration and monitoring features.

For more information on migrating your Apache installation to IIS 6, see "Migrating from Apache to IIS 6," (Chapter 8), p.137.