Check an Autonomous System Number (ASN) for IP ranges or lookup an IP address to get details of the AS. To find ASN's belonging to an organisation, simply enter a search string. A comma separated list of matching ASN's will be returned.
An AS is a connected group of one or more IP prefixes run by one or more network operators which has a SINGLE and CLEARLY DEFINED routing policy. This number is used in both the exchange of exterior routing information (between neighboring ASes), and as an identifier of the AS itself.