To help ensure optimum availability of your applications to users who need them, you need to do more than ensure that the network is available and that your server is up and running. You need to set availability goals, configure IIS to meet the demands that users are placing on your applications, and test your applications for functional compatibility with IIS 6.0 worker process isolation mode.

To be certain that the level of application availability on your server meets the needs of your customers; you must first establish availability, service, and request-handling goals that accurately represent those customer needs. Next, you need to create application pools, and then configure IIS features to isolate applications and to tune and monitor your application pools. Finally, you need to assess the tradeoffs between availability and other aspects of running your applications, such as performance.

To help maintain high availability of the applications that your server hosts, you can use two kinds of testing: compatibility testing and comparison testing. Functional compatibility testing verifies that your applications will work with the IIS 6.0 worker process isolation mode features that you have enabled. Comparison testing measures the availability of your applications against your application availability goals, which reveals how closely the day-to-day availability of applications hosted on your server matches your original goals.

Before you begin this process, you must:

•	Install the Microsoft® Windows® Server 2003, Standard Edition; Windows® Server 2003, Enterprise Edition; Windows® Server 2003, Datacenter Edition; or Windows® Server 2003, Web Edition operating system with the default options.
•	Install IIS 6.0 with the default settings by using Add or Remove Programs in Control Panel.

If you use other methods for installing and configuring Windows Server 2003, such as unattended setup, or enabling IIS 6.0 by using Manage Your Server, then the default configuration settings might not be identical to the configuration settings described in this section.

When you complete the process for ensuring application availability, you will meet the basic requirements for achieving high availability for your applications. You will set and begin to measure availability goals for your applications based on your business needs. Your applications will be configured to make effective use of IIS 6.0 features. Also, you will know whether your applications are compatible with IIS 6.0 worker process isolation mode.