Welcome to WebmasterWorld Guest from 184.108.40.206
Header unset Cache-Control
AFAIK, the Apache directives are case sensitive...
Directives in the configuration files are case-insensitive, but arguments to directives are often case sensitive.
If you prevent indexing, wouldn't that automatically prevent caching and archiving?
And apparently I don't understand the role of a cache. Why would Google need it if the page isn't in the index and a public cashed copy can't be shown.
Placing those files in a robots-blocked directly sounds like it would solve the problem. However, it would take a lot of time to change the links to about 1,000 files.
Header set X-Robots-Tag "noindex"
apparently I don't understand the role of a cache. Why would Google need it if the page isn't in the index and a public cashed copy can't be shown.
... server header for one of the PowerPoints ...
encyclo: If the header is not there, then I would suspect that the files are not actually being served by the Apache server. This may well be because you have a forward-proxy (nginx) handling static files, so the .htaccess is not called in that situation.
Header set X-Robots-Tag "noindex,nofollow,noarchive"
on subsequent requests for the resource google sends the If-Modified-Since header.