{"uid":"cap_AuasaJzsyJ63OMH-FwKw1","slug":"reverse-dns-ptr-lookup-via-nextdns-6e2dbd01","name":"Reverse DNS PTR Lookup via NextDNS","description":"Reverse DNS (PTR) of an IPv4 address as answered by NextDNS: the hostname(s), TTL and response code, plus whether the PTR's forward A record points back (forward-confirmed reverse DNS). Compare resolvers for stale or filtered answers. $0.01 per lookup.","url":"https://ip.intel.rallylive.ca/ip/ptr/via/nextdns?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$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","properties":{}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","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":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_vtwRStXyF9Be3aBg71Y7t","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Performs a reverse DNS (PTR) lookup for an IPv4 address using NextDNS as the resolver, returning hostnames, TTL, response code, and forward-confirmed reverse DNS (FCrDNS) status.","exampleAgentPrompt":"What's the reverse DNS hostname for 203.0.113.42 as seen by NextDNS, and does the PTR's A record point back to the same IP (forward-confirmed)?","exampleUseCases":[{"title":"Email server PTR validation","prompt":"Check the reverse DNS for 198.51.100.25 via NextDNS — I need to know the PTR hostname, whether it's forward-confirmed, and the TTL so I can troubleshoot why our mail is being rejected."},{"title":"Comparing resolver PTR answers","prompt":"Run a PTR lookup on 104.21.14.200 through NextDNS and tell me the hostname and response code — I want to compare it against what another resolver returns to see if NextDNS is filtering or giving stale answers."},{"title":"Security investigation of suspicious IP","prompt":"I'm investigating a suspicious connection from 45.33.32.156 — can you do a reverse DNS lookup via NextDNS and tell me what hostname it resolves to and whether the forward DNS confirms it?"}],"resultDescription":"Returns the PTR hostname(s) associated with the IPv4 address as resolved by NextDNS, along with the DNS TTL, response code (e.g. NOERROR, NXDOMAIN), and a boolean or flag indicating whether the PTR record is forward-confirmed (the hostname's A record resolves back to the original IP).","failureModes":["IP has no PTR record (NXDOMAIN response)","NextDNS filters or blocks the PTR query, returning SERVFAIL or empty","PTR exists but A record does not point back (FCrDNS fails)","Invalid or non-routable IPv4 address input","Timeout or upstream NextDNS resolver unavailability","Payment failure for the $0.01 USDC per-call fee"],"whenToPreferThis":"Use this endpoint when you specifically want to see how NextDNS resolves PTR records — useful for comparing resolver behavior, detecting filtered or stale PTR answers, or validating FCrDNS for mail server deliverability from the NextDNS perspective. Prefer this over generic PTR lookups when resolver-specific behavior matters.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-11T18:43:33.776Z","isFirstParty":false,"canonicalSlug":"reverse-dns-ptr-lookup-via-nextdns-6e2dbd01"}