[TriLUG] OT: CDNs using DNS IPs to geolocate?

[Aaron Joyner]

1) You type "www.example.com" into your web browser.
2) Your computer asks your DNS server to resolve "www.example.com" to an IP
address.
3) Your DNS server talks to Example Corporation's DNS server (which might
be run on their behalf by Akami, et. al.).
4) The server in (3) looks at the source IP address of the incoming
request, consults a table to see where you're located, and based on that
gives you back the "closest" server IP address for www.example.com.
5) Your DNS server caches that response, and returns it to you (and all
future clients, until the TTL expires).
6) You contact the IP address provided to your DNS server in (4).

Thus, if you choose to use a DNS server in Taiwan, you might get suboptimal
service (for a host of reasons, this only one).
Aaron S. Joyner

PS - I left out an awful lot of steps along the way, but these are the
salient details for your question.  :)


On Tue, Jan 7, 2014 at 1:02 PM, Brian <lugmail at cheetah.dynip.com> wrote:

> Hi Smart People,
>
> I recently came across the following sentence:
>
> "[L]arge content delivery networks (CDNs) like Akamai and LimeLight still
> use the IP address of the DNS server to judge your location."
>
> How does a CDN host know what DNS server I used to resolve their name?
>
> ~B
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