Over the past week, while trying out a number of different free visitor tracking services, I've noticed some interesting discrepancies. I access the internet from a number of different points. Depending on the tracking service I've used, one access point alternately shows up as either of two cities, neither of which I live in.

The reason for this sort of thing is two-fold. First, a bit of background. At one time, the Whois database that tracked all domain registrations was a single database. Now, it's been spread out to over 100 copies, many of which do not agree with each other. In the course of business, Internet Providers may change their own nameserver information. Specifically, they may change the address information of where their nameservers live. So one Whois database might have one city registered for a particular IP address block, and another database may have a different city for the same block.

What city a particular IP address gets converted now depends on what Whois database a particular visitor tracking service uses. And herein lies part of the secret of how I will hopefully, eventually, develop an IP-to-City conversion system in the postings of this blog. However, without manual editing, any such database that you build cannot possibly be 100% accurate, as IP address block information can and does change.

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