Leosghost - 11:36 pm on Jun 30, 2012 (gmt 0)
I spoke at length with Maxmind when I first began using them ..They told me that their data base ( particularly at city/ town level ) was constantly updated when the new users of their system logged in..So as I was the first to use their system from my small Brittany town, they then knew that my fixed IP was corresponding to that map location and could use it , as they use all of their customers locations, to fine tune their system..
Also some of the French ISPs ( mine is one of them ) add a 3 letter code to the dslam and the end customer IP ( mine in this case ) ..so the complete string helps them narrow it down even more ..it gives out the town code , the unique dslam number , the "department" ( corresponds to "county" in the UK ) number, and finally the IP number..
Testing the script I use for cities and towns with their data base using their "live service" , and contacts in other towns around the world tends to lead me to believe that many other ISPs as well as those mentioned by IncrediBill add these "extras"in the reverse DNS..
The one thing that might throw you off a little is AOL customers..Maxmind did warn that in Western Europe for example, all AOL customers in France, the UK and Germany, and maybe other countries appear as UK IPs due to AOL procedures..
Google apparently does not use a system as accurate, as adsense frequently serves me German ads..