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

Edward Lewis Ed.Lewis at neustar.biz
Tue Dec 14 15:02:13 UTC 2010

At 11:52 -0200 12/13/10, Carlos Martinez-Cagnazzo wrote:
>Hello all,
>>  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?
>That would certainly be the expected behaviour. Otherwise, they are
>doing something wrong.

Funny how things go 'round and 'round.  Not too many years ago we 
wished applications, and specifically web browsers, wouldn't use 
their own caches.  Back then, applications would do a look up and 
then use that information for the life of the process. The problem 
was that the process lifetime sometimes exceeded the TTL of the 
resource record.

If an application does cache DNS data, the behavior should be the 
same as a DNS server/cache.  That is, honor the TTL.

To answer the originator's question, if the TTL on www.example.org A 
(or AAAA) is 3600 and you click on one link at 9am and the other at 
10:05am, there should be two DNS requests.  If the clicks were 9am 
and 9:05am, then I would excuse a second stub resolver-like request 
to a cache which should hit on the previous click.

OTOH, it's never a crime to ask the same question again and again.
Edward Lewis
NeuStar                    You can leave a voice message at +1-571-434-5468

In going through my family medical history I recently realized I was
born with congenital amnesia.  I couldn't even remember my name at birth.

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