On Mon, 17 Apr 2006, Ryan Malayter <[EMAIL PROTECTED]> wrote
On 4/17/06, Guillaume Filion <[EMAIL PROTECTED]> wrote:
MaxMind provides a free IP->City database
http://www.maxmind.com/app/geolitecity
The actual latitude/longitude is, according to Google Maps:
46.786632/-71.280305. That's a pretty good match.
I tested the a few IPs with known locations, and it seems the MaxMind
data is much more accurate than hostip.info. If their free version is
"free enough" for this project, basing a resolver on that should work
well. It would make choosing the correct country zone almost automatic
at the very least.
Their free version gets you down only to country level, and doesn't work
well with AOL subscribers (always appear to be in the US).
How accurate you need to be, and can be, is worth thinking about. For
the UK, I think getting the country right is probably enough. Of three
geo databases I've tried, hostip puts me in London, another (can't
remember which now) in Glasgow, and MaxMind in Stoke-on-Trent (probably
a misunderstanding of the fact that my ISP is based in Stoke
Mandeville). In fact, I'm in Warwick, but in network terms Hostip is
probably most useful as my ADSL line is terminated in London. All in
all, knowing my town / city is probably of limited value in working out
which server is closest, as long as you know I'm in the UK.
Even knowing the specific network isn't necessarily that useful.
62.3.237.50 is another ADSL host on the same ISP as me, about 27 ms
away. But that trip involves going into London and back out again - only
three hops, but two along ADSL lines. 83.245.15.97 is a co-lo box of
mine in London. Different network, a lot more (11) hops, but only 15ms,
almost all of which falls in the first hop.
But for bigger countries you may need to narrow down the geographical
information a bit more - it's a long way from DC to LA. It's going to be
a balance and it's never going to give perfect results, but it seems
there is good scope to improve things a lot over what we have at
present.
--
Chris Hastie
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