ASN Lookup (IP to AS Number)
Find the origin AS number, AS name, BGP route (prefix), country and RIR for any IP address. Routing data from Team Cymru.
What this ASN lookup tool does
Every public IP address is announced to the Internet by an Autonomous System (AS) — a network operated by an ISP, hosting provider, cloud or enterprise. This tool maps an IP to its origin AS number, the AS name, the covering BGP prefix, the registration country and the managing RIR. The routing data comes from Team Cymru's IP-to-ASN service.
How to read the result
- AS number — the network that originates the route in BGP (e.g.
AS15169is Google). A prefix can occasionally have more than one origin AS. - BGP route (prefix) — the most specific block currently seen in the global routing table that contains your IP.
- RIR — which regional registry (ARIN, RIPE NCC, APNIC, LACNIC, AFRINIC) administers the address space.
To see the registrant and abuse contact, use the IP Lookup tool, which queries RDAP. To check whether the prefix is cryptographically authorised for that AS, use the RPKI/ROA validator.
Frequently asked questions
What is an ASN (Autonomous System Number)?
An ASN is a globally unique identifier for a network that has its own routing policy on the Internet. ASNs are handed out by the RIRs and used in BGP to exchange routes between networks.
Why does an IP sometimes return more than one AS?
Most prefixes have a single origin AS, but multi-origin routing (MOAS) and route leaks can make the same prefix appear with several origins. It can be legitimate (anycast, migrations) or a sign of a hijack.
Is ASN data the same as geolocation?
No. The country shown is the RIR registration country of the address block, not the physical location of the device. For accurate city-level location you need a dedicated geolocation database.