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Re: Geo location to IP mapping

  • From: Alain Hebert
  • Date: Mon May 15 19:11:51 2006


(In a more precise manner)

I originaly stated that below country (aka, province/state, city, zip, etc) it wont be very reliable because in my experience we spread that /20 without the hierarchy you expect.


. We have subnets on LanEx going outside the city, province/state and even country;

. We concentrate compagny with 10 to 50 sites using private ip and a single internet point;

. We have dynamic ip users using cable, dsl, dialup and even long-distance dialup;


I'm sure peoples have many more of hierarchy situation like this one.


None really, short of having access the real infrastruture of the ISP.

I'm sure the IP Location Industry have deals with the major ISP to get their DB more precise.

But if the targeted IP is on a smaller outfit the quality of the informations will not be the same. This is why I stated that globally the state/city should be pretty low (50%).

That good that you have 75% to 85% but I wasn't ignoring the AOL's in my statement.

That's all.

(FYI: The NTP Issue has been resolved (;-} )

Kevin Day wrote:

On May 15, 2006, at 4:36 PM, Alain Hebert wrote:

We use a Geo/IP location database. It's surprisingly accurate, with a few exceptions.

The company we purchased the database from uses a number of sources of data, to produce something pretty accurate:

1) WHOIS records for the IP assignment
2) WHOIS records for domain in the PTR record for the IP
3) Parsing the PTR record for city names and airport codes
4) Purchasing IP/billing and shipping city,state,zip records from sites with accurate records (e-commerce and other sites that people need to enter their local info)
5) All of the above for the hop or two before the end in a traceroute
6) BGP and traceroute comparisons to determine where the boundaries are in how you've internally routed things

Even if you're just allocating from a single /20, you probably have some hierarchy, and that can be picked up through routing or DNS or SWIP.

Comparing the database to the IP that our customers used to make purchases we exceed 95% accuracy in identifying the country, and 75-85% in city/state. The big exception is AOL, since their IP assignments are pretty well randomized with respect to geography.

Never underestimate what can be done through regular expressions and an army of people sitting at terminals in China to verify what can't be automated. :)

For those of you really interested, email me privately and i'll dump what we have on record for a block or two of yours.

Alain Hebert [email protected] PubNIX Inc. P.O. Box 175 Beaconsfield, Quebec H9W 5T7
tel 514-990-5911 fax 514-990-9443