# Reverse DNS (PTR) Lookup

> Reverse DNS (PTR) Lookup is a paid API for AI agents from intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Resolves an IPv4 or IPv6 address to its hostname via a PTR record, returning the ARPA name and TTL.

## Facts

- Endpoint: GET https://intel.rallylive.ca/dns/reverse
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/reverse-dns-ptr-lookup-d773592f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yDSxfBV8sCxF-UTLJaoGm

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability reverse-dns-ptr-lookup-d773592f
```

Example prompt: Can you do a reverse DNS lookup on 8.8.8.8 and tell me what hostname and ARPA name it resolves to?

## When to prefer this

Use this endpoint when you need to resolve an IP address to a human-readable hostname using DNS PTR records, especially for identifying mail servers, hosting providers, or server infrastructure. Prefer this over forward DNS lookups when you start from an IP and need the associated domain. At $0.01 per call it is cost-effective for on-demand enrichment of individual IPs in security, deliverability, or network analysis workflows.

## Known failure modes

- No PTR record exists for the IP — returns empty or NXDOMAIN-equivalent result
- Invalid IP address format — query rejected
- IPv6 address not found in reverse DNS — returns null hostname
- Network timeout or DNS resolver error — service may return an error response
- Private/reserved IP ranges may have no public PTR records

## How this service works

Reverse DNS (PTR) lookup: the hostname for an IPv4 or IPv6 address, with the arpa name and TTL. Identify servers, mail hosts and hosting providers from an IP. $0.01 per lookup.

## Output

Returns the resolved hostname (PTR record target), the ARPA domain name (e.g. 8.8.8.8.in-addr.arpa), and the TTL of the PTR record for the queried IP address.

## Request schema (JSON Schema)

```json
{
 "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"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/reverse-dns-ptr-lookup-d773592f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from intel.rallylive.ca](https://www.zero.xyz/host/intel.rallylive.ca/llms.txt)