Comment by tallytarik

Great post and a great little tool. Some of my experience using these techniques in production:

1. Trilateration mostly doesn't work with internet routing, unlike GPS. Other commenters have covered this in more detail. So the approach described here - to take the closest single measurement - is often the best you can do without prior data. This means you need a crazy high distribution of nodes across cities to get useful data at scale. We run our own servers and also sponsor Globalping and use RIPE Atlas for some measurements (I work for a geo data provider), yet even with thousands of available probes, we can only accurately infer latency-based location for IPs very close to those probes.

2. As such, latency/traceroute measurements are most useful for verifying existing location data. That means for the vast majority of IP space, we rely on having something to compare against.

3. Traceroute hops are good; the caveat being that you're geolocating a router. RIPE IPmap already locates most public routers with good precision.

4. Overall these techniques work quite well for infrastructure and server IP addresses but less so for eyeball networks.

https://ping.sx is also a nice comparison tool