How Geolocation Databases Guess Where You Are

An address lookup returning a city name looks like a measurement. It is an estimate assembled from several indirect sources, and understanding which sources contributed explains why some results are precise and others are absurd.

Registry records set the outer bound

Regional registries record which organisation was allocated each range and the country associated with that allocation. This is the foundation layer and it is reliable at country granularity, most of the time.

It is unreliable below that, because an allocation covers wherever the operator chooses to deploy the addresses. A range registered to a company headquarters may serve subscribers hundreds of miles away.

Operators can publish more granular self-reported data describing how they have distributed their ranges. Whether they do, and whether they keep it current, varies enormously.

Latency measurement narrows the estimate

Providers of geolocation data operate measurement points around the world and time how long responses take from each. Round-trip times constrain the physical distance an address can be from each point.

Triangulating from enough vantage points produces a plausible region. The technique works because light speed sets a hard floor on latency that no amount of network engineering can beat.

It degrades where routing is indirect. Traffic that crosses an ocean before reaching its destination measures as distant from everything, which is why some results land in the middle of nowhere.

Network type determines accuracy

Fixed broadband geolocates comparatively well, because equipment is physically installed and address ranges are usually deployed regionally.

Mobile networks geolocate badly. Translation concentrates subscribers at gateway sites, so a device is reported at the gateway rather than where the person is, and gateways serve wide areas.

Corporate and satellite networks are worse again, since traffic can egress through a single facility on another continent from where the user sits.

Privacy services relocate the answer entirely

Any relay, proxy or corporate tunnel means the lookup describes the exit point. The result is correct about the traffic and wrong about the person.

Some privacy services deliberately select exits near the user to preserve regional content, which produces roughly plausible answers while still breaking any assumption of precision.

Because these services are widely deployed by default on some platforms, the share of traffic where geolocation describes infrastructure rather than a user has grown steadily.

Confidence should be carried with the answer

Serious geolocation data ships with a stated accuracy radius and a confidence value. Consuming only the city name discards the part that tells you whether to trust it.

Systems that act on location, whether for content rules or for risk decisions, need to treat a low-confidence result as missing data rather than as a fact worth enforcing.