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I found out how to get all the IP addresses via Server Logs.

I'm using the IP addresses to get the Latitude and Longitude. The address appear to be approx 1 3 miles away from the actual address of the vistor.

Can someone explain why the GPI coordinates via IP address are not exactly matching the location of the user?

Is there a more dependable way to get the address?


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What are Google AP and GPI? – Lèse majesté Jan 27 '11 at 0:43
up vote 0 down vote accepted

This is mostly because IP address -> location databases are not updated in real time with what ISP's actually allocate. It is conceivable that a single /20 or /22 block serves a 10 mile region of customers, or approximately 10 - 15 DSLAM units.

Services such as Maxmind typically keep close to in sync with IP allocation changes, and have a very high accuracy rate by city. However, lat / long for any given IP address could jitter by 5 - 10 miles, depending upon who receives that IP from any given ISP, in any given city.

The larger the actual subnet, the larger the jitter where this is concerned. For instance, an ip on a /16 block could literally be anywhere in a given 30 mile radius especially if the ISP assigns a new IP on each connection. It is seldom that they allocate that way, but some do. There's no way to keep a database in sync with such a moving target.

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