{"uid":"cap_MeIk_LsKyBEKyWAtbOuaq","slug":"sitecheck-web-intel-cymru-asn-lookup-f8282795","name":"SiteCheck Web Intel – Cymru ASN Lookup","description":"Maps an IPv4 address to its origin AS number, the BGP prefix that covers it, the country, the registry and the allocation date, using Team Cymru's public IP-to-ASN DNS service. Returns no origin when Cymru has no mapping for the address.","url":"https://api.webintel-api.workers.dev/api/security/cymru-asn-lookup?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["ip"],"properties":{"ip":{"type":"string","description":"IPv4 address such as 8.8.8.8 (required)"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_YRez4MilGCXm_2nxKwboY","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Resolves an IPv4 address to its origin AS number, BGP prefix, country, registry, and allocation date using Team Cymru's IP-to-ASN DNS service.","exampleAgentPrompt":"Can you look up the ASN, BGP prefix, country, and registry for the IP address 203.0.113.45 using Cymru's IP-to-ASN data?","exampleUseCases":[{"title":"Investigate suspicious inbound traffic","prompt":"I'm seeing a lot of traffic from 185.220.101.55 — can you tell me which autonomous system and country that IP belongs to, and when that prefix was allocated?"},{"title":"Enrich threat intelligence report","prompt":"I need to enrich my threat report: look up the origin AS number, BGP prefix, and RIR registry for the IP 45.142.212.100."},{"title":"Network troubleshooting for ops team","prompt":"We're debugging a routing issue — can you find which ASN and BGP prefix covers 1.1.1.1, and which regional internet registry allocated it?"}],"resultDescription":"Returns the origin AS number (e.g. AS15169), the BGP CIDR prefix covering the IP (e.g. 8.8.8.0/24), the two-letter country code, the RIR name (ARIN, RIPE, APNIC, etc.), and the allocation date. Returns no origin if Team Cymru has no mapping for the address.","failureModes":["IP not found in Cymru's database — returns no origin/empty mapping","Invalid IPv4 address format — likely 400 or validation error","Private/reserved IP ranges (RFC1918, loopback) may return no result","Cymru DNS service temporarily unavailable — upstream timeout","Rate limiting or payment failure due to x402 protocol issues"],"whenToPreferThis":"Use this endpoint when you need authoritative BGP routing context for an IPv4 address — specifically the ASN, prefix, RIR, and allocation date — sourced from Team Cymru's well-known passive DNS dataset. Prefer this over generic WHOIS or geolocation APIs when you need routing-layer data rather than registrant contact details or city-level geolocation.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-24T12:44:51.484Z","isFirstParty":false,"canonicalSlug":"sitecheck-web-intel-cymru-asn-lookup-f8282795"}