  The geographical location of Internet IP addresses has an importance both for
academic research and commercial applications. Thus, both commercial and
academic databases and tools are available for mapping IP addresses to
geographic locations. Evaluating the accuracy of these mapping services is
complex since obtaining diverse large scale ground truth is very hard. In this
work we evaluate mapping services using an algorithm that groups IP addresses
to PoPs, based on structure and delay. This way we are able to group close to
100,000 IP addresses world wide into groups that are known to share a
geo-location with high confidence. We provide insight into the strength and
weaknesses of IP geolocation databases, and discuss their accuracy and
encountered anomalies.
