# dns-a-backup-subdomain

> dns-a-backup-subdomain is a paid API for AI agents from dns.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-20).

Looks up the DNS A record for the 'backup' subdomain of a given domain via Cloudflare DoH and reports its existence, IP records, and TTL.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/host/backup/a?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/dns-a-backup-subdomain-2d46c611
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_wUChO4m8GlRDXiqkRg7mJ

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 dns-a-backup-subdomain-2d46c611
```

Example prompt: Can you check if backup.acme.com exists in DNS — I want to know if the backup subdomain is configured and what IP it resolves to.

## When to prefer this

Use this endpoint when you need a quick, targeted check on whether a specific domain has a 'backup' subdomain configured in DNS, without needing to enumerate all subdomains. Ideal for infrastructure audits, failover validation, or existence checks where you already know the host label is 'backup'.

## Known failure modes

- Domain does not have a backup subdomain — returns no records found
- Invalid or malformed domain input — may return an error or empty result
- Cloudflare DoH upstream timeout — lookup may fail with a network error
- NXDOMAIN response if the subdomain definitively does not exist
- Rate limiting or payment failure resulting in no response

## How this service works

A record of backup.<domain>: looks up the backup host under the domain you give (A via Cloudflare DoH) and reports whether it exists, its records and TTL. Quick existence check for common hosts like backup without enumerating subdomains. $0.01 per lookup.

## Output

Returns whether the A record for backup.<domain> exists, along with any resolved IP addresses and the TTL of the record. If no record is found, indicates absence.

## 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/dns-a-backup-subdomain-2d46c611/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from dns.intel.rallylive.ca](https://www.zero.xyz/host/dns.intel.rallylive.ca/llms.txt)