# DNS CNAME Lookup for smtp Subdomain

> DNS CNAME Lookup for smtp 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 CNAME record for the smtp.<domain> subdomain using Cloudflare DNS-over-HTTPS and returns whether it exists, its records, and TTL.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/host/smtp/cname?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-cname-lookup-for-smtp-subdomain-1c9e142d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ofVOiQOhx8DFYtZOZ1xmJ

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-cname-lookup-for-smtp-subdomain-1c9e142d
```

Example prompt: Can you check if smtp.example.com has a CNAME record — I want to know what it resolves to and whether it actually exists?

## When to prefer this

Use this endpoint when you need a fast, targeted check of whether smtp.<domain> has a CNAME record without performing full subdomain enumeration. Ideal for email infrastructure auditing, pre-connection checks, or validating third-party mail relay delegation. Prefer this over generic DNS resolvers when you specifically need smtp subdomain CNAME data routed through Cloudflare DoH with a simple per-lookup pricing model.

## Known failure modes

- Domain does not exist — returns NXDOMAIN or no records found
- smtp subdomain has no CNAME record (may have A/AAAA instead) — returns empty or missing record
- Invalid or malformed domain input — may return error or unexpected result
- Cloudflare DoH upstream timeout — lookup may fail or return incomplete response
- Rate limiting or payment failure — request rejected before DNS lookup occurs

## How this service works

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

## Output

Returns whether the smtp.<domain> CNAME record exists, the resolved CNAME target(s), the TTL value, and the DNS response code (e.g. NOERROR or NXDOMAIN) as answered by Cloudflare DNS-over-HTTPS.

## 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-cname-lookup-for-smtp-subdomain-1c9e142d/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)