IP Lookup: How It Works
An IP lookup reports what a public address reveals: the network that owns it, the organisation behind that network, and an approximate location. The word doing the most work in that sentence is 'approximate' — and this page explains how approximate.
What a lookup can tell you
| Field | Reliability |
|---|---|
| Country | 95–99% — registry data, rarely wrong |
| Region / state | 55–80% |
| City | 50–75% — often the ISP's hub, not the user |
| Coordinates | Indicative only; frequently a regional centroid |
| ISP / organisation | High — from registry allocations |
| ASN | Definitive — allocated and published |
| Proxy / VPN / hosting flags | Moderate, and constantly changing |
Location does not come from the address itself — an IP contains no geographic information. It comes from databases built by combining registry records, ISP-published data, network latency measurements and user-submitted corrections. That is why two providers can disagree about the same address.
The centroid problem
When a database knows the country but not the city, it returns a point representing the country. For years the default coordinates for the United States pointed at a farm in Kansas, whose residents received sustained harassment from people who believed criminals were operating from their property. It is a useful illustration of what these coordinates actually are: an admission of uncertainty rendered as a precise-looking pair of numbers.
Why the result is often wrong for a real person
- Mobile networks route through a small number of gateways, so a phone in one city commonly appears in another hundreds of kilometres away.
- Carrier-grade NAT puts thousands of subscribers behind a single address.
- Corporate VPNs present the company's exit point, not the employee's location.
- Consumer VPNs and proxies deliberately present somewhere else.
- Cloud and hosting addresses point at a data centre, which is where a server is but never where a person is.
IPv4 and IPv6
IPv4 offers about 4.3 billion addresses and ran out years ago, which is why carrier-grade NAT is now standard and why an address rarely identifies one household. IPv6 offers 340 undecillion, enough for every device to have a unique public address — which improves routing and, at the same time, removes the incidental privacy that address sharing provided.
Legitimate uses
- Choosing a default language, currency or content region.
- Fraud signals — flagging a login from an unexpected country.
- Routing to the nearest server or CDN edge.
- Aggregate analytics at country level.
- Complying with regional licensing or regulatory boundaries.
What it is not adequate for is identifying an individual, proving where someone was, or making a consequential decision about a person. Courts have repeatedly found that an IP address identifies a connection, not a person — several people, and often several networks, sit behind one.
Privacy note
Your IP address is visible to every server you connect to; that is how responses reach you. Anyone can look it up. A VPN replaces it with the provider's address, moving your visibility from your ISP to that provider — which is a shift in who you trust, not an elimination of trust.