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IIS stripping the "If-Modified-Since" header

9:15 pm on Jan 8, 2010 (gmt 0)

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Re: [webmasterworld.com...]

I have been having the same problem that you mention. One solution I found is using Helicon ISAPI_Rewrite module installed in IIS 6.

The idea is to add a header X-If-Modified-Since that is a copy of the header If-Modified-Since. This can be done in ISAPI_Rewrite by adding the following lines to the httpd.ini file:

RewriteCond If-Modified-Since: (.+)
RewriteHeader X-If-Modified-Since: ^$ $1

Then I can access the new header in any ASP script (by the new name) even with 404-redirect turned on.

Something similar may be possible with Microsoft's rewrite module [iis.net] for IIS 7 that some hosting providers now use.

Hope this helps.

[edited by: marcel at 9:32 pm (utc) on Jan. 8, 2010]
[edit reason] Removed specifics [/edit]

9:28 pm on Jan 8, 2010 (gmt 0)

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Many thanks for that Simon! :)

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