And possibly other things?
Following discussion in the thread [
webmasterworld.com...] last week re: Google Chrome Instant I delved into the X-Purpose (aka X_Purpose) header.
It seems Safari has long used this for the Top Ten Sites preview in their browser, which puts a small extra load on a web server - or larger if you have a site that's popular with Mac users).
Now Google Chrome, based on Safari, has begun using X-Purpose to indicate a kind of pre-fetching ("We'll show you pages much faster than..." What?!).
A week ago I coded a response to both that would return a 200 instead of the 403 I would normally return. I arranged to accompany the code with a brief piece of text saying why they couldn't have the real page.
Why code 200?
I'm not worried about the Preview - that is just a desktop thing - but the return code is part of the same response coding. The real reason for returning 200 was to by-pass google, which claims it blacklists the pages (in the browser only, but...) if it sees anything other than a 200. In the thread linked to above, someone states that "blacklist" refers to the preview only, but google's text is ambiguous and there is no point taking chances, what with google now listing fewer and fewer real pages in SERPS.
NB: I also caught a Chrome asking for a Preview (but no Instant). So far, apart from that single instance, I have had one chrome browser asking for Instant views of half a dozen pages, two of which were my "report your problem here" pages (which they don't seem to have done). I have not yet worked out how they got to those report pages.
