Service packs are the typical means by which ISA Server 2006 hotfixes and modifications are distributed. You can install the latest service pack to help keep your product up to date. Service packs include updates, administrative tools, drivers, and other components. These items are bundled together in a single package that you can download.
Service packs are cumulative. Each new service pack contains all the fixes that are included in previous service packs, together with any new fixes. You do not have to install a previous service pack before you install the latest service pack.
For more information about how to install ISA Server 2006 hotfixes and updates, click the following article number to view the article in the Microsoft Knowledge Base:
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How to install ISA Server hotfixes and updates