BGP Route Lookup — ASN & Prefix Information

BGP is the routing protocol that exchanges reachability information between autonomous systems on the public internet. Each AS announces IP prefixes it can deliver traffic to. Knowing which prefixes an organization announces helps validate whether an IP truly belongs to that network or was hijacked.

Our lookup surfaces registry-held ASN metadata plus optional prefix lists so you can correlate addresses seen in logs with registered network operators without logging into multiple RIR portals.

Query by AS number when researching a provider's full footprint — cloud regions, anycast ranges, and acquisition networks often appear as multiple prefixes under one ASN. Query by IP when triaging a single suspicious address from firewall alerts.

ASN input triggers prefix enumeration when the upstream BGP API responds successfully. IP input focuses on mapping that specific address to its parent AS and organization name.

Each prefix entry represents a CIDR block announced in BGP. The prefix count field shows total IPv4 announcements even when we display only the first twenty for readability. Large providers may announce hundreds of blocks — the sample still confirms AS identity.

Missing prefix data does not invalidate ASN metadata. Transient API failures fall back to registry-only results with an explanatory note in the JSON payload.

When latency spikes toward a destination, confirming the destination's AS and upstream registry helps distinguish provider issues from last-mile problems. Compare ASN from this tool with traceroute AS paths for consistency.

Capacity planners estimating whether a partner can accept new cross-connects review announced prefix sizes to gauge address holdings without requesting internal spreadsheets.

Route hijacks occur when an AS announces prefixes it does not own. Sudden origin AS changes for prefixes you operate warrant investigation. This tool establishes baseline ownership — pair with RPKI validation and monitoring services for continuous assurance.

Incident responders paste attacker IPs to identify hosting providers for abuse reports. ASN and organization fields feed into ticket templates sent to network operations contacts.

Registry indicates which regional Internet registry delegated the ASN — useful when determining legal jurisdiction for data requests. Country reflects registration metadata, not necessarily physical server location.

Organization name strings come from WHOIS and geolocation databases. Acquisitions may lag rebranding — verify critical decisions against multiple sources.

BGP data reflects routing tables at query time. An AS may withdraw or announce prefixes minutes later. We do not maintain historical BGP timelines on this page — use dedicated collectors for long-term analytics.

Private AS numbers and RFC 1918 space never appear in public BGP. This tool targets public internet routing only.

Combine with IP lookup for city-level geolocation and with WHOIS for contact handles. Reverse DNS may reveal hostnames within announced prefixes.

Shared hosting detection shows co-tenant domains on an IP while BGP lookup shows the provider's AS-level identity — complementary views of the same infrastructure.

Integrators call the extended API with action bgp-route-lookup and a query parameter containing ASN or IP. Parse prefixes array, prefixCount, and asn fields in JSON responses.

Cache ASN metadata longer than prefix lists because registry data changes infrequently relative to routing dynamics.

Students learning internet architecture connect abstract BGP concepts to real AS numbers they recognize — public DNS resolvers, major CDNs, university networks. Prefix lists illustrate CIDR aggregation in production.

Lab exercises ask learners to compare their home ISP ASN with datacenter ASNs after deploying cloud VMs, observing how address ownership shifts with infrastructure choices.