1. With Network Measurement
   1. Delay-based
      1. ShortestPing
         1. A very simple delay-based technique for estimating the location of an IP. All landmarks are probing pings to the target. Then, the RTT time is computed, and the location of the target can be specified as the nearest landmark (minimum RTT).
            1. Each target is mapped to the landmark that is closest to it in terms of round trip time (RTT).
      2. GeoPing
         1. Determines the geographic location of an Internet host by taking advantage of the network delay and the geographic distance.
            1. It is motivated by the observation that hosts with similar network delays are geographically located close to each other.
   2. Octant
      1. This approach transforms the problem to a error-minimizing constraint satisfaction.
         1. Speed of Internet(SOI)
            1. SOI is a variation of CBG. Its motivation can be derived from the observation that the geographic distance between hosts on the internet is typically much less than the limit due to speed of light propagation
   3. Topology-Based (TBG)
      1. It is an extension of CBG in a way that (a) it augments delay measurements to end-hosts with information about topology and routing and (b) it performs constraints multilateration in all the intermediate routers and end-hosts (targets) simultaneously
         1. Constraint-Based (CBG)
            1. The main idea in CBG is to estimate the distance between the landmarks and the targets using delay measurements, create constraints based in these distances, and finally apply them in a multilateration process to geolocate the targets
2. Without Network Measurement
   1. Database
      1. The most popular and basic approach to identify the location of an IP is to keep and manually maintain a database. The database is used to match an incoming IP (internet protocol) address to the country, region, state, city, latitude, longitude and Internet service provider (ISP) of the Internet user.
         1. GeoTargetIP
         2. GeoIP
         3. IP2Country
   2. String Matching
      1. It infers the location of an IP based on the DNS names of the host of interest or other nearby network nodes. It is an intuitive method for locating internet hosts. It relies strongly on the fact that DNS names contain meaningful location information
         1. GeoTrack