All the regional registries maintain databases that can be queried using the whois command, however it is sometimes necessary to try several registries. Here's an example of a registry being queried to determine the ownership of an IP network. RIPE is the European Internet registry. The full list of whois servers is whois.arin.net whois.apnic.net whois.nic.mil rs.internic.net whois.ripe.net Details of the physical locations and ownership of IP networks are available on the World Wide Web in the IP Network Index . The key to high level internet routing is the grouping of Internet hosts into autonomous systems which usually correspond to commercial or administrative entities.
All autonomous systems have a distinctive and unique number.
Details of autonomous systems are available from the whois servers in the same way as details of IP networks. Unfortunately the syntax of such queries differs between the various servers, the ripe server requires ASnnnn whereas the arin server requires just the number.