# DKIM Selector 'sm' Lookup

> DKIM Selector 'sm' Lookup 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 and parses the DKIM public key for the 'sm' selector of a given domain via Cloudflare DoH, returning key type, length, testing flag, and revocation status.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/dkim/sm?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/dkim-selector-sm-lookup-26656d7c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KiU1OZrCw7H4XvR5vmjMx

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 dkim-selector-sm-lookup-26656d7c
```

Example prompt: Can you check the DKIM 'sm' selector for example.com — I want to know if the key is valid, what type and length it is, and whether it's revoked or in testing mode?

## When to prefer this

Use this endpoint when you specifically need to inspect the 'sm' DKIM selector (used by some email service providers) for a domain. Prefer this over a generic DNS TXT lookup when you need structured parsing of DKIM fields (v=, k=, key length, testing flag, revocation) rather than a raw TXT string. Choose this over manual DNS tools when automating email authentication audits or deliverability checks at scale.

## Known failure modes

- Domain does not have an sm._domainkey TXT record — returns not found or empty result
- DNS resolution failure via Cloudflare DoH — transient network error
- Malformed TXT record that cannot be parsed into DKIM fields
- Empty p= field indicating revoked/disabled key, flagged explicitly
- Rate limiting or payment failure for the $0.01 per lookup fee

## How this service works

DKIM public key for selector "sm" of a domain: looks up sm._domainkey.<domain> (TXT, Cloudflare DoH) and parses v=, k=, key type, public-key length, testing flag and whether the key is revoked (empty p=). Confirms that mail signed with the sm selector will verify. $0.01 per lookup.

## Output

Returns parsed details from the sm._domainkey.<domain> TXT record including: DKIM version (v=), key type (k=), RSA/EC public key and its bit length, whether the selector is in testing mode (t=y flag), and whether the key is revoked (empty p= field). Confirms whether mail signed with the sm selector will successfully verify.

## 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/dkim-selector-sm-lookup-26656d7c/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)