[Telecom] DNS usage
- From: danny burstein <dannyb@xxxxxxxxx>
- Date: Tue, 27 Nov 2007 12:18:04 -0500 (EST)
In <xtCdnRyTeZkfhtHanZ2dnUVZ_szinZ2d@xxxxxxxxxxxxxxxx> Joseph Bender <jcbender@xxxxxxxxxxxxxxxxxxxxxxxxxxx> writes:
Interestingly Cox used to suffer from frequent DNS failuers but over theMany ISPs have overloaded DNS servers. I run my own caching
past year or so that's gotten much better.
recursive lookup server on my firewall at home. Easier that way.
Just wondering about that issue, and I may be showing
my complete ignorance here....
In the Good Old Day if you looked up a web page there
was one DNS query for that specific URL, and typically
the relevant info was cached by your own system for a bit
so when you went to the next page in that file, you already
had the IP address.
Nowadays, though, each web page may include a dozen
advertisements or other add-ons. And they'll be
changing minute by minute.
Would this be be a noticable increase in DNS load?
Thanks
--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@xxxxxxxxx
[to foil spammers, my address has been double rot-13 encoded]
***** Moderator's Note *****
Since most ads are served by a separate IP address, the answer to your
question is "Yes, it does increase DNS traffic by a _lot_".
It also allows Doubleclick and similar advertising providers to track
your internet usage across different sites: each URL for an ad
includes a code that identifies the site and page you're viewing, and
the Doubleclick servers use the information to build a profile of your
surfing habits and thus target ads to you based on what you've looked
at in the past.
Since putting these ads on your browser depends on a lot of DNS
lookups, there's a simple solution: break the DNS lookup for
advertisements, so they never appear on your screen! Once you do that,
you'll get both better privacy and a great boost in speed.
Your computer actually checks three places for DNS info:
1. The HOSTS file on your computer is checked _first_. This is
a legacy from the days of ARPANET, before DNS was deployed:
each domain name had to have a matching IP address stored
on each computer, and it's still in use.
2. The DNS cache is checked next.
3. If _both_ checks fail, your machine will perform a DNS
querry to match the URL to an IP address.
Ergo, you need only "poison" your HOSTS file to prevent your browser
from attempting to retrieve ads. Your computer will look at the HOSTS
file, find a dummy entry, and then attempt to retrieve the ad from an
invalid IP address, usually the "Loopback" address, which points back
to your own machine.
There are several sources for ready-to-use HOSTS files which contain
poisoned entries for most major advertising servers, but I'll refrain
from mentioning them here. Google is your friend: they're not hard to
find.
Bill Horne
Temporary Moderator
.
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