Do "regular" browsers ever return a 304?

[Marcia]

I've never, ever seen it - only seen 200's, ever with a regular browser. However, Googlebot just deep crawled a site that was moved to a new host (they do look for last_modified, I understand) and right off a Mozilla agent dived right in and came up returning a 304 on the site's pages.

I've never seen that, could there be anything "unusual" going on, or is it normal?

[Marcia]

Just came across this post, which was what I was kind of wondering when I saw the 304's

msg #12

Doesn't Google send out Googlebots that have their User-agent listed as IE or Firefox, and from different IPs, so it can't be identified as having anything to do with Google? Seems to me this would be a very efficient way of identifying fraudulent sites. It doesn't take long to find a site that serves up different pages to Google than it does to a regular browser.

[webmasterworld.com...]

[claus]

Uhm.. it's the server that returns a 403, not the browser.

That said, my log from two days ago shows 62 different UA's that received a 304. Two of them were these:

Googlebot/2.1 (+http://www.google.com/bot.html)
Mozilla/5.0 (compatible; Yahoo! Slurp; [help.yahoo.com...]

Others were IE, Firefox, and Safari. What they will see is the exact same page as a request that gives a "200 OK". Not sure if this answered anything though...

[lammert]

Return code 304 is "Not modified since last retrieval". It is not a browser return value, but returned by your host to tell the browser the content did not change compared to a given date.

Maybe Googlebot uses the date check to reduce bandwith usage. Are sure it was caused by a bot, and not by a new browser like FireFox for example?

<added>
You said that you moved to a new host. Maybe the settings of the webserver of your new host are different and they return a 304 more often to save bandwidth.
</added>

[Just Guessing]

I've seen Googlebot getting 304s on static pages for a year or so, I think.

I've tried coding PHP pages to test if modified since requests and return 304s, but no matter what logic I use, Googlebot still gets 200s on my PHP pages.

[Marcia]

Return code 304 is "Not modified since last retrieval". It is not a browser return value, but returned by your host to tell the browser the content did not change compared to a given date.

Exactly, understood. And Gbot looks for that.

BUT - why then, is it being returned with 304 for some visitors and with 200 for other visitors - all on the same day, for the same pages? That is what dosen't make sense to me.

Added:
I simply did the title wrong on this thread - but the issue is still there - I have never seen the server return a 304 with a "normal" Mozilla visit.

[claus]

>> why then, is it being returned with 304 for some visitors and with 200 for other visitors

I'm still not sure if i understand you right, but there's a quite simple explanation for this, as some browsers will never have requested that file before, and hence there will be no "last visit". These will get a "200 OK" just like the browsers whose last request to that file is before the date that your server checks. (ie. they visited the page before the last time it was updated)

Those that get the 304 will be those that have already visited the same page after the last time it was updated.