Some Web servers do not recognize the "Accept-Encoding:gzip" header in the requests that are forwarded by ISA Server 2006

Consider the following scenario:

• In Microsoft Internet Security and Acceleration (ISA) Server 2006, you configure an HTTP access rule.
• You enable HTTP compression to request compressed data.

In this scenario, ISA Server 2006 adds the header "Accept-Encoding:gzip" to the requests that are forwarded to the Web servers. However, there is no space between the colon and the "gzip" token. Therefore, some Web servers do not recognize this header and then disconnect from ISA Server 2006.

To resolve this problem, apply the hotfix rollup package that is described in the following Microsoft Knowledge Base article:

To work around this problem, do not configure ISA Server 2006 to request compressed data.

Section 4.2 of Request for Comments (RFC) 2616 does not mandate a space in the header. However, RFC 2616 recommends that you use a space . Some Web servers are not fully compliant with the RFC and do not parse the "Accept-Encoding:gzip" header correctly.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: