IIS Does Not Return an HTTP 304 Not Modified Message for Compressed Content

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This article was previously published under Q307633

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SYMPTOMS

When you use HTTP compression, Internet Information Services (IIS) sends the complete HTML page instead of responding with an HTTP status code "304 Not Modified" message. This occurs even if the HTML page has not been modified.

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CAUSE

If a browser includes the length attribute in the GET request, IIS compares the length of the compressed page with the length that is submitted by the browser. Because the browser sends the size of the uncompressed page, IIS submits the page again.

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WORKAROUND

Do not use HTTP compression.

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RESOLUTION

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 (http://support.microsoft.com/kb/260910/EN-US/ ) How to Obtain the Latest Windows 2000 Service Pack

The English version of this fix should have the following file attributes or later:

   Date        Time   Version        Size    File name 
   ----------------------------------------------------
   11-Oct-2001 15:16  5.0.2195.43   337,680  Asp.dll
   11-Oct-2001 15:16  5.0.2195.36   299,792  Fscfg.dll
   11-Oct-2001 15:16  5.0.2195.43     8,464  Ftpctrs2.dll
   11-Oct-2001 15:16  5.0.2195.43     6,416  Ftpmib.dll
   11-Oct-2001 15:16  5.0.2195.43     9,488  Httpmib.dll
   11-Oct-2001 15:16  5.0.2195.44    13,584  Infoadmn.dll
   11-Oct-2001 15:16  5.0.2195.44   245,520  Infocomm.dll
   11-Oct-2001 15:16  5.0.2195.44    62,736  Isatq.dll
   30-May-2001 00:03  5.0.2195.36     3,584  Spmsg.dll
   11-Oct-2001 15:16  5.0.2195.43     7,440  W3ctrs.dll
   11-Oct-2001 15:16  5.0.2195.44   348,432  W3svc.dll

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STATUS

Microsoft has confirmed that this is a problem in IIS 5.0. This problem was first corrected in Windows 2000 Service Pack 3.

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APPLIES TO

Microsoft Internet Information Services 5.0

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kbhotfixserver kbqfe kbbug kbfix kbwin2000presp3fix kbwin2000sp3fix KB307633

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Retired KB Content Disclaimer

This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.

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