# dns-a-app-subdomain

> dns-a-app-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 2026-10-21).

Looks up the A record for the app.<domain> subdomain via Cloudflare DNS over HTTPS and returns whether it exists, its IP records, and TTL.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/host/app/a?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/dns-a-app-subdomain-ac249468
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_MkcZ4kNLacWUnxz5JpxXn

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-app-subdomain-ac249468
```

Example prompt: Can you check whether app.acmecorp.com has an A record in DNS — I need to know if that subdomain exists and what IP it points to?

## When to prefer this

Use this endpoint when you need a fast, targeted check on whether the app.<domain> subdomain is configured in DNS without performing broad subdomain enumeration. Prefer this over general DNS resolvers when you specifically need the 'app' host, want Cloudflare's DoH infrastructure for reliability, or need a simple pay-per-lookup approach with no setup.

## Known failure modes

- Domain does not exist (NXDOMAIN) — returns no records and a non-existent response code
- app subdomain not configured — returns empty record set with NOERROR or NXDOMAIN
- Invalid or malformed domain input — may return error or empty response
- Cloudflare DoH upstream timeout or outage — service may fail to respond
- Network or resolver error — may return an error status rather than DNS data

## How this service works

A record of app.<domain>: looks up the app 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 app without enumerating subdomains. $0.01 per lookup.

## Output

Returns whether the app.<domain> A record exists, the resolved IP address(es), the TTL value, and the DNS response code as answered by Cloudflare DoH.

## 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-app-subdomain-ac249468/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)