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ASN lookup
Find the origin networks observed for a public IP, or look up an autonomous system number and its holder. Routing observations are not subscriber identities.
Find the origin networks observed for a public IP, or look up an autonomous system number and its holder. Routing observations are not subscriber identities.
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Enter an autonomous system number such as AS15169, a plain decimal ASN, or a public IPv4 or IPv6 address. Select Look up to request the relevant result. An ASN lookup for an address reports the matching prefix and origin networks observed by the source. A query for a number reports that autonomous system's holder description and origin visibility. These are related views, but they answer different questions.
The ASN lookup does not accept a complete website URL, a domain name, a private IP or dotted ASN notation. For a domain, use DNS lookup to inspect the relevant A or AAAA records first, then submit the address you actually want to investigate. A domain can resolve to several addresses, so preserve which answer you selected rather than treating one result as the entire service.
An autonomous system number identifies a network within interdomain routing. It is different from an individual IP address, a domain name or a subscriber account. IANA allocates number resources to regional internet registries, which make assignments under their policies; see the IANA ASN registry. An ASN lookup helps place an address observation in network context.
One autonomous system can originate many prefixes, and a company can operate more than one autonomous system. A service may also use infrastructure belonging to other organizations. Therefore, an ASN lookup should not be reduced to a universal answer to “who owns this user?” The network identifier is useful for routing and operational questions while remaining insufficient to establish a person's identity.
For an IP query, read the matching BGP prefix and every origin ASN returned. The RIPEstat Network Info endpoint supplies this association from RIPE RIS information and documents an eight-hour dump basis. The ASN lookup fetch time describes when we obtained the response; it does not claim that the underlying routes were measured at that exact instant.
For a number query, the holder field is the name reported through RIPEstat's WHOIS source. Origin visibility follows the source's threshold, rather than a test of whether the whole network is online. Its AS Overview documentation explains that a transit-only network can return a negative origin status. ASN lookup keeps this distinction visible instead of labeling that network as down.
A source can return more than one origin ASN for a matching prefix. The tool preserves that list. Do not silently choose the first result and describe it as the only network involved. Multiple origins deserve context from the operator, the observation period and more detailed routing evidence. An ASN lookup alone cannot determine whether the situation is intentional, transitional or erroneous.
The result provides a separate lookup action for each returned number. Use it to inspect the corresponding holder overview while retaining the original IP-to-prefix observation. A second ASN lookup answers the number question; it does not replace the earlier evidence about the specific address. Record both when the distinction matters in an operational report.
An address registration describes a resource allocation or assignment. A routing observation describes how a prefix appears in the source's collected routing data. These records can name different organizations for legitimate reasons. A hosting arrangement, address lease or network relationship may affect who operates the route. Neither field should be relabeled as the verified owner of every device using the address.
Use IP WHOIS lookup when the question concerns address registration and ASN lookup when it concerns the autonomous system view. Keep the source and time attached to each. If the answers differ, preserve the difference rather than merging the names into one unsupported identity. The mismatch may be the useful fact that tells an operator what to investigate next.
A number and holder name do not establish the physical location of a particular subscriber or server. Large networks can operate across many regions, and a public source can belong to a VPN, relay or shared gateway. An ASN lookup that returns a familiar company still cannot place the user's device at that company's headquarters or identify the person behind the request.
For a location issue, read why IP location can be wrong. Keep estimated geography separate from registration and routing. Combining these categories into one confident map pin can make an interface look informative while making the conclusion less reliable. ASN lookup provides one part of the evidence, with a deliberately narrower meaning.
Some ASN values are reserved for private use, documentation or other special purposes. This tool classifies those published ranges without sending them to RIPEstat. It does not invent a public holder. The private-use ranges include 64512–65534 and 4200000000–4294967294; documentation ranges include 64496–64511 and 65536–65551. The classification also distinguishes reserved values and the AS_TRANS transition number.
An ASN lookup for a private-use value can explain its category, but that value is not globally unique to one internal network. Two independent organizations can use the same private number. Likewise, an example ASN in a technical document is not evidence of a real public operator. Keep the classification beside the result when explaining it to someone else.
Routing collectors observe the routes available through their participating peers. A missing prefix or origin in one source is not a universal proof that no route exists anywhere. A timeout, rate limit or provider error is a different condition again. The ASN lookup reports request failures explicitly and leaves unavailable fields unset instead of converting absence into a negative security verdict.
This interface does not perform traceroute, test packet delivery, enumerate every prefix belonging to an ASN or validate route origin authorization through RPKI. Those tasks require different data and methods. An ASN lookup should help you choose the next appropriate investigation, not imply that one organization label certifies routing correctness, ownership, reachability or trustworthiness.
Start with a concrete symptom and a time. Perhaps a public source differs after joining a VPN, or an application team asks which network originates an address in its logs. Submit the relevant address, retain the returned prefix and origins, then inspect the number overview when useful. Include the data source and its collection limits in the report.
Compare like with like. An ASN lookup for your browser's IPv4 exit may differ from the result for its IPv6 source. A phone on cellular and a laptop on Wi-Fi can also use different networks in the same room. Preserve the actual queried addresses and connection context privately so the recipient can understand the comparison rather than guessing from organization names alone.
No. The visible network can be a parent organization, infrastructure supplier, VPN exit or another intermediary. An ASN lookup provides network context, not your billing relationship. Compare the observation with the service architecture you actually use and confirm uncertain relationships with the provider. A surprising name is a reason to investigate, not evidence of wrongdoing by itself.
No. The status uses the source's defined observation threshold and can be negative for a transit-only network. It is not a direct availability check. Preserve the source query window when supplied and test the affected destination separately. Do not report an outage solely because an ASN lookup does not show origin visibility in this particular view.
The result contains no fraud score or abuse verdict. Many independent users and services can share a large network, and registration information does not establish individual conduct. Use the methodology to understand how this site separates observations from conclusions. A useful ASN lookup ends with clearly labeled evidence and a justified next step, rather than a claim that the number itself proves someone is safe or malicious.