Autonomous System Lookup
Autonomous Systems advertising network prefixes into the public Internet for inter-domain routing can be observed in BGP snapshots. These snapshots can be used to easily determine the origin of a prefix (a prefix-to-AS dataset is hosted by CAIDA) and infer the business relationships between networks (the AS relationships dataset is also hosted by CAIDA). This page uses these datasets, coupled with AS name mappings (hosted by Geoff Huston).
Feel free to use this page to query an AS number you'd like more information on. Note that this page only recognises AS numbers in asplain format. Asdot and asdot+ formats are not (yet) supported. See rfc5396 for more information on AS number formats.
The data here is not necessarily accurate; datasets may have been captured at differing points in time. It is, however, informative, and possibly reliable for tasks which are not mission-critical.
The information hosted on these pages is updated once per week. For an alternative representation of the same data, a full list of ASes, their connections, descriptive names, and advertised address blocks, is available at http://www.dcs.gla.ac.uk/~sds/current_as_ip_mappings.