ISA Server Does Not Cache Responses That Contain the Location Header

Internet Security and Acceleration (ISA) Server does not cache responses that contain the Location header. (For example, in a Network Monitor trace, under the HTTP protocol in the headers section: Location:Http://domain.com).

Location headers are sometimes used in links that redirect a user to a site based on certain criteria. The link itself may contain only parameters for a query that is run on the Web server. The response to that query is an URL to which the user is being redirected. This URL is sent to the browser as a Location header, the browser then goes to that location.

With ISA Server, the problem can occur if the caching options are set to cache all content including dynamic content and a scheduled content download job is set to download and cache such a site; the links that return location headers are not cached, even though the sites that are returned by the links are cached (provided that the download job specifies the proper depth of links to follow). When such a site is later accessed, ISA Server needs to access the original link and gets the response (the Location header). The site that is referenced in the response is served from the cache.

It may be appropriate in certain situations for ISA Server never to contact the original site but only to serve content from cache. The hotfix that is listed in this article makes ISA Server cache responses that contain Location headers as well.

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language. The English version of this fix should have the following file attributes or later:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.