Deano’s answer to: “How are IP addresses mapped to location?”

At the top of the Internet addressing food chain, the Internet Assigned Numbers Authority (IANA) keeps track of IP addresses assigned across the globe, and meted out through the various Regional Internet Registries (RIRs).

(Photo courtesy Cisco Systems)

Internet Service Providers (ISPs) are the ones who assign IP addresses to a given customer, in a given place.

For smaller ISPs, their total service area is very geo-specific to a given city/county, which means that all of their IP address pool, purchased and assigned from an upstream “backbone provider” (also an ISP in most cases), will also be specific to that location/area.

Larger ISPs, which are more likely to “own their own backbone”, purchase their IP address space from one or more RIRs or National Internet Registries (NIRs) and could centrally manage their entire IP address space from a single location… But they too choose to sub-divide their address pool into smaller, localized service areas. This serves several purposes:

• It enables the ISP techs to associate issues with an IP address to a physical service map in case an on-site tech need be assigned,
• distributes the number of points of failure, and works in concert with their Disaster Recovery and Redundancy plans to ensure outages are localized as much as possible, and
• it allows the ISP to easily absorb smaller, more local ISPs through acquisition in a smoother manner (making these customers part of a new – if redundant – local service area, rather than adding them to some larger base of users, and confusing them with existing service plans/infrastructure.

IP address geo-mapping companies simply take the information on file with ISPs, NIRs, RIRs, and the IANA; they then create mappings between IP addresses and country/state/city/neighborhood/node locations.

This information used to be highly erratic and outdated, especially once one went “below country level”. These days, however, everyone along the IP assignment chain understands the value in having accurate IP maps in place, even down the the individual node level (at least, this is true in developed countries) – and as such, this information tends to be updated exclusively electronically, from the on-site technician on up the chain.

As a result, you’re now easier to track, service, and yes, even prosecute based on your IP address alone. Thank heavens for the neighbor’s unprotected WiFi!

Answer originally appeared on Quora: How are IP addresses mapped to location?