About the ASN / ISP Lookup
The ASN and ISP lookup identifies the autonomous system and registered network information associated with a public IP address or ASN. It is useful for understanding which organization originates a route and which network block contains an address.
How to use this tool
Enter a public IPv4 or IPv6 address, or an autonomous system number such as AS13335. For an IP query, review the matched prefix and origin ASN. For an ASN query, inspect the registered name and related routing or registry fields returned by the data source. Compare results with a live BGP route collector when you need time-sensitive routing visibility, because registration and routing answer different questions.
How to read the result
An autonomous system number identifies a network participating in interdomain routing. The origin ASN is the system announcing a prefix in BGP, while a registered organization or ISP name describes administrative data associated with the resource. A prefix is the address block covered by the route. Hosting providers, transit networks, CDNs, and customer organizations can appear in different roles, so the displayed name is not always the consumer-facing ISP.
Limits and privacy
ASN and registration datasets can lag route changes, transfers, mergers, and multi-origin announcements. An address can be announced by a partner or mitigation provider without changing the underlying registrant. The result does not identify an individual subscriber or prove ownership of traffic. Private and reserved addresses are rejected, and the submitted IP or ASN is processed through the buffer.lol API for the lookup.
Common questions
- What is the difference between an ASN and an IP address?
- An IP identifies an interface or routed endpoint. An ASN identifies a network that exchanges routing information for one or more IP prefixes.
- Is the ASN always the same as the ISP?
- Not always. The announcing network may be a cloud, transit, CDN, security, or enterprise provider rather than the subscriber's retail ISP.