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Reverse DNS PTR Lookup via NextDNS
x402
Reverse DNS PTR Lookup via NextDNS is a paid API for AI agents from ip.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).
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.
Price / call$0.01
Success—
StatusUnknown
How this service works
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.
Output
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).
Example use cases
Email server PTR validation
“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.”
Comparing resolver PTR answers
“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.”
Security investigation of suspicious IP
“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?”
Technical details
Endpoint
GEThttps://ip.intel.rallylive.ca/ip/ptr/via/nextdns?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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