[dns-operations] Behavior of browsers with absolute HTML links (Was: compressing

Joe Greco jgreco at ns.sol.net
Fri Dec 10 14:33:42 UTC 2010

> On Wed, Dec 08, 2010 at 09:17:03AM -0600,
>  Joe Greco <jgreco at ns.sol.net> wrote 
>  a message of 57 lines which said:
> > Back in the infancy of the Web, relative links were king, and some
> > web pages only generated one DNS lookup to enable the page to load,
> > and many other pages only had at most a handful.
> > 
> > By today's count, and I did just count, pulling up www.ebay.com
> > results in *204* lookups, www.cnn.com results in 92 lookups,
> > Facebook 24, etc.  That's actual requests happening on the wire per
> > tcpdump.  (I'm actually a bit shocked.)
> What is the behaviour of a Web browser when there are several
> *asbolute* links with the same "prefix"? I would have assume that two
> links <http://www.example.org/foo.html> and
> <http://www.example.org/bar.html> create only one DNS request?

Links shouldn't generate DNS requests simply for existing, but
other fetches such as images do.  I'm guessing that's what you

So something like


Yeah, it's only supposed to generate one lookup for www.sol.net
and the application ought to cache that for a bit.  Although it
is interesting, it worked that way on initial load, but upon a
click on "reload" it generated three requests (I have no idea
where *three* would be coming from, two or thirteen might make
sense given the data on the page).

Or did you mean when clicking on a link in a page?  In my 
experience, that'll happily use the existing cached data.

... JG
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.

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