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#258008 - 10/06/2005 21:43 Random cookies coming from Google?
DWallach
carpal tunnel

Registered: 30/04/2000
Posts: 3810
I've got my browser set to notify me when cookies show up and I've noticed something lately. I'll Google for some business (today it was "berryhill", a local Mexican chain). Then, while the Google results page comes up, I get a request to set a cookie for "berryhilltamales.com" (the correct destination, but still...).

Is this some service that Google is offering to third parties to help them track keyword searches? Any ideas?

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#258009 - 10/06/2005 22:00 Re: Random cookies coming from Google? [Re: DWallach]
Mataglap
enthusiast

Registered: 11/06/2003
Posts: 384
I assume those cookies come from the ads on the results page, even though they're just text ads. I haven't bothered to dig into the source.

--Nathan

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#258010 - 10/06/2005 22:47 Re: Random cookies coming from Google? [Re: Mataglap]
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7058
Loc: Pittsburgh, PA
Dan, I'm pretty sure what you're seeing is the results of Google's prefetch behavior:

<link rel="prefetch" href="http://www.berryhilltamales.com/"><a href="http://www.berryhilltamales.com/"><b>Berryhill</b> Baja Grill - We put the Ahhhh in Baja!</a>

Check this for more info:
http://www.google.com/help/features.html#prefetch

That link tells you how to disable prefetch in Firefox, which was the first thing I did when I learned about this, because I think prefetch is a scourge upon mankind.

Incidentally, Google ads can't set cookies on behalf of other sites, because cookies can be set only via HTTP headers, and only for the domain that request connects to. If the ads were frames/images which resulted in another background request, that'd be a different story.
_________________________
- Tony C
my empeg stuff

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#258011 - 11/06/2005 00:05 Re: Random cookies coming from Google? [Re: tonyc]
tman
carpal tunnel

Registered: 24/12/2001
Posts: 5528
Quote:
That link tells you how to disable prefetch in Firefox, which was the first thing I did when I learned about this, because I think prefetch is a scourge upon mankind.

Hrm. Didn't know about that. I've disabled it as well.

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#258012 - 11/06/2005 09:51 Re: Random cookies coming from Google? [Re: tonyc]
DWallach
carpal tunnel

Registered: 30/04/2000
Posts: 3810
Prefetching, huh? That certainly makes sense. Now I guess the decision is whether I'm more interested in performance or privacy. Hmm...

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#258013 - 11/06/2005 17:04 Re: Random cookies coming from Google? [Re: DWallach]
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7058
Loc: Pittsburgh, PA
Quote:
Prefetching, huh? That certainly makes sense. Now I guess the decision is whether I'm more interested in performance or privacy. Hmm...

To me, those goals are not at odds with each other. By turning off prefetch, you avoid the cookies, and you also avoid the background HTTP request, which is pulling down links that you haven't yet decided you want to visit. Now, maybe for your tamales example, it just so happens that what you were looking for ended up being the first link, but more often than not, for me anyway, it's rarely that simple.

From what I've seen, they seem to only use prefetch for the top result, and not all the time, only when they've decided you're "probably" interested in that link based on your query. Thing is, if you really are going after the first link, isn't it just saving you the second or so it takes you to click that link?

Google usually does the right thing, but I think this prefetch business is a flat-out bad idea that needlessly increases traffic usage for both clients and servers, with very little benefit. But maybe I just don't "get it."
_________________________
- Tony C
my empeg stuff

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#258014 - 11/06/2005 18:21 Re: Random cookies coming from Google? [Re: tonyc]
DWallach
carpal tunnel

Registered: 30/04/2000
Posts: 3810
Well, prefetching could help in a couple ways:

- If your DNS server sucks (as SBC's server, on the other side of my DSL connection, often does), this gets that lookup done before you click on the link.

- If the prefetch is for something that I want, then when I click on it, I'll already have the base HTML file, so I'll see something immediately. Probably not a big deal for DSL, but potentially a bigger win for modem users. And, if done properly, any long-running prefetches could be prematurely cancelled once you've discovered that the prefetch wasn't helpful.

- Prefetching definitely places additional load on servers, but the extent of that load is directly related to how accurate the prefetch is at predicting future behavior. If the prefetch is accurate, then the additional server load is zero.

Thinking it over, I'd say that prefetching the DNS query would be the right answer for my needs. Hmm...

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#258015 - 11/06/2005 19:08 Re: Random cookies coming from Google? [Re: DWallach]
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7058
Loc: Pittsburgh, PA
Or maybe just use a better DNS server? When my ISP's DNS has sucked, as it currently does, I've just found others that were faster. For quite a while now, I've been using 4.2.2.1 and 4.2.2.2 which are (for me) a lot faster than any of about six or seven Adelphia DNS servers I've tried.
_________________________
- Tony C
my empeg stuff

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