How accurate is IP address / Geocode lookup?

Jeff Chastain wrote: > I have a client that is looking to ascertain the state ( or country if not > US based ) of the current visitor to their web site.  One possibility has > been to use their IP address and a geocode lookup, which I have never done the location you often get is where the IP block owner is located. for country level, IP lookups are > 90% accurate (our geoLocator CFC stops at country/locale info). accuracy drops off the smaller the administrative unit you want to find, where the client is physically located (somebody along a state/province border could go either way) & the ISP involved (AOL is a famous extreme case where every user's state, etc. is "AOL" & satellite-based ISPs will also screw you up even at the country level). that said, if you're not using the location to deliver packages or drop bombs it's probably good enough, especially if you use a manual fallback mechanism. there's supposedly more accurate means of measuring where a given IP is physically located: http://www.sustainablegis.com/blog/cfg11n/index.cfm?mode=entry&entry=831F21D5-20ED-7DEE-2AFB50CC1481BAC1