ISAPI Filters Marked as Unknown Are Called before Filters with Priority (237471)

We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx

SUMMARY

ISAPI Filters that do not register with either High, Medium, or Low priority are marked as Unknown in the Microsoft Management Console (MMC). Filters marked as Unknown are called before all filters with any of the three priorities that have registered for the same notification.

MORE INFORMATION

The priority of the installed filters is a read-only metabase property. To find the priority of the installed filters, you can either use the MMC or one of the available metabase utilities. The three metabase priority properties are NotifyOrderLow, NotifyOrderMedium and NotifyOrderHigh, and are available in the following locations:

/LM/W3SVC/Filters/Filter
/LM/W3SVC/n/Filters/Filter

Where Filter is the name of the installed filter and n is the Web Server instance.

If two or more filters have the same priority and have registered for the same notification, the FilterLoadOrder determines which is called first. Note that Global Filters installed under the Master WWW Properties are called before a filter with the same priority installed under one of the Web Server instances.