# Reverse DNS via DNS.SB Change Watch

> Reverse DNS via DNS.SB Change Watch is a paid API for AI agents from ip.intel.rallylive.ca, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-11).

Monitors reverse DNS (PTR record) lookups for an IP address via DNS.SB and alerts when the result changes compared to the previous check.

## Facts

- Endpoint: GET https://ip.intel.rallylive.ca/watch/ip/ptr/via/dnssb?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/reverse-dns-via-dns-sb-change-watch-5e2c8e7b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_oxsBJZJt04RovA6AeC23t

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-via-dns-sb-change-watch-5e2c8e7b
```

Example prompt: Keep an eye on the reverse DNS for 203.0.113.42 and let me know if the PTR record ever changes from what it was last time you checked.

## When to prefer this

Choose this endpoint when you need to detect changes in reverse DNS (PTR records) for a specific IP address over time, especially for automated monitoring or alerting workflows. It is ideal when you want diff-style output (before/after field values) rather than just the current PTR record, and when you need persistent state tracking across calls without managing your own baseline storage. Prefer it over a plain reverse DNS lookup endpoint when change detection and scheduling are the goal.

## Known failure modes

- IP address not provided or invalid format — query fails with input error
- No previous result stored (first call for this IP) — 'changed' will be indeterminate or false with no diff
- DNS.SB resolution failure or timeout — may return an error or empty PTR result
- Previous result expired (older than 90 days) — baseline lost, treated as first call
- Rate limiting or payment failure for $0.02 USDC per call

## How this service works

Change watch for reverse dns via dnssb: runs the check, compares it with the result from your previous call for the same ip (kept 90 days) and returns the current answer, changed true/false, the fields that changed with before/after values, and when it was last seen. Schedule it to be alerted when this changes. $0.02 per check.

## Output

Returns the current PTR record result for the IP (via DNS.SB), a boolean 'changed' flag, a list of fields that changed with before and after values compared to the previous call for that IP (retained for 90 days), and the timestamp of when it was last seen.

## 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-via-dns-sb-change-watch-5e2c8e7b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ip.intel.rallylive.ca](https://www.zero.xyz/host/ip.intel.rallylive.ca/llms.txt)