How to assign IP to the visitor's country?

[ggttaa]

I would like to know, how companies such as MaxMind collect their "country databases". I know, there are many records and each range of the IPs represents some country... But, my question is: How the companies assign some IP range to the appropriate country? Have they some information from the ISPs? Have you any idea? Thank you very much.

[gregbo]

Some of the information comes from the RIRs (RIPE, ARIN, etc.). Some can be gleaned from doing reverse DNS lookups. (This is not always reliable and can be costly.) Some ISPs publish their netblock assignments.

If you have to use geotargeting, make sure the people you are providing information to understand its limitations.

[dataguy]

Do a search on "IP to Country". There's at least 1 website which provides the lookup table for free. I implemented this about 2 months ago and it totally changed my perspective of my members. It also helps us to detect fraudulent users. Highly recommended.