How to use this tool
ASN & Prefix Lookup: interpretation and next steps
Use ASN & Prefix Lookup to identify who a network resource belongs to, whether it is globally announced, and which origin ASN RIPE RIS currently observes. It is a fast first check before configuring a session, investigating a route, or comparing provider information.
What this check answers
The lookup combines RIPEstat registry and routing data. Registry allocation blocks describe where a resource is administered; they do not grant ownership or prove a route is reachable. Treat the observed origin and timestamp as a routing snapshot.
Workflow
- Enter an ASN such as AS3333, or a CIDR prefix such as 193.0.0.0/21.
- Check announcement state, holder, registry block, and observed origin ASN.
- Open the raw response when a downstream system needs the original source fields.
Example and limits
For AS3333, the result identifies the RIPE NCC holder and whether RIS currently sees originated prefixes. For a prefix, compare the observed origin with the ASN that you expect to announce it.
- A transit-only ASN can be active but show no originated prefixes.
- Global routing visibility is not the same as contractual ownership.
Frequently asked questions
Is this a WHOIS replacement?
It is a routing-focused summary of RIPEstat data; use the RIPE Database for authoritative object editing.
Why is an ASN not announced?
It may be transit-only, newly assigned, filtered by visibility thresholds, or not currently originating a route.
Can I use an IP address?
Use the containing CIDR prefix for the most useful routing result.