[Telecom] DNS usage

>Interestingly Cox used to suffer from frequent DNS failuers but over the

>>past year or so that's gotten much better. >> > Many ISPs have overloaded DNS servers. I run my own caching >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 snipped-for-privacy@panix.com [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

Reply to
danny burstein
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Yes.

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The better way to do this is to use Firefox, install Adblock Plus, and select from any number of preconfigured blocklists. While HOSTS poisoning works, it can lead to stalling browsers and broken page layout, while an intelligent adblocker will preserve this.

Reply to
Joseph Bender

I'll second Firefox and AdBlock Plus. Another good one is FlashBlock although that recently fouled me up when trying to view blip.tv videos. I finally whitelists blip in FlashBock and now everything works fine.

One thing that would be interesting to discover is why all of a sudden Vonage's Account Activity site doesn't work with Firefox, but works fine with IE.

Reply to
T

Getting back to the original questions:

danny burstein wrote in :

Just for the hostname part, to be pedantic about it ;)

Depending on operating system, local resolver and browser.

Most probably.

Yes, lots of adservers use DNS tricks in order to be able to make rapid changes which defeats the caches at your ISP, in your OS and in your browser (although not all use the timetolive data correctly). With added DNS tricks and redirects so you will get stuff from a server in the same part of the world or from a content-delivery network when you are visiting a big and popular site.

Yes! A lot. The other increase is from anti-spam measures: a lot of anti-spam measures use information distributed via DNS which means quite a number of lookups are done to deliver an e-mail. Although this won't affect the resolver that you use for your home (unless you run your own mailserver) but it will affect the resolver for the mailserver of the ISP.

Koos van den Hout

Reply to
Koos van den Hout

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