# payload402 DNS Liveness Lookup

> payload402 DNS Liveness Lookup is a paid API for AI agents from payload402.edgebytenet.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).

Checks whether a hostname resolves by querying A and AAAA DNS records via Cloudflare DNS-over-HTTPS

## Facts

- Endpoint: GET https://payload402.edgebytenet.workers.dev/dns/lookup?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/payload402-dns-liveness-lookup-653673d1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1o9rtZ2sbZ-bg5wwYWTs3

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 payload402-dns-liveness-lookup-653673d1
```

Example prompt: Before you try to crawl example.com, can you check if that hostname actually resolves in DNS — does it have A or AAAA records?

## When to prefer this

Use this endpoint when an agent needs a fast, reliable DNS liveness check before attempting to crawl, link to, or connect to a hostname — especially when you want Cloudflare's global DNS resolver backing the check without setting up your own DNS client. Prefer this over generic HTTP reachability checks when you specifically need DNS-layer resolution (A/AAAA records) rather than full HTTP connectivity validation.

## Known failure modes

- Domain does not resolve — returns hasA: false and hasAAAA: false with empty records array
- Invalid hostname format passed as input — may return an error or empty result
- Cloudflare DoH upstream outage — may cause request failures or timeouts
- Payment not provided or invalid — HTTP 402 response blocking the DNS query
- Rate limiting if too many requests are sent in quick succession

## How this service works

npm package license triage for coding agents: call before npm install or adding a dependency mid-task. Returns declared license, SPDX normalization, and permissive-default compatible yes/no/unknown from the public npm registry. Triage only — not compliance-grade SBOM or legal advice. Workflow: call GET /license/check (or MCP check_npm_license) before npm install; if compatible=no, pick another package or escalate to human; if unknown, treat as risk. Example: left-pad@1.0.0 before install. Also: Convert amounts between ISO 4217 currencies using ECB daily reference rates (Frankfurter). Use for invoices, travel budgets, expense reports, and shopping comparisons when you need a verifiable rate instead of LLM arithmetic. Not live tradable FX — rates follow ECB business-day publication. Also: Resolve a place name or lat/lon to IANA timezone and coordinates (Open-Meteo). Use for agent scheduling, travel logistics, and local-time questions without LLM guessing. Not IP geolocation. Also: Translate short text between languages (Azure Translator). Use when an agent needs a verifiable string in another language for UI copy, messages, or research snippets — not legal, medical, or certified translation. Also: English Wikipedia fact lookup: search by query or exact title, returns intro extract as plain text. For agents that need a grounded summary before deeper web search. Not a substitute for primary sources. Also: Ranked search results (English Wikipedia): titles, article URLs, and snippets from MediaWiki search. Same SERP-shaped JSON as web search APIs; index is Wikipedia only — not the open web. Pair with GET /wiki/lookup for intro text.

## Output

Returns a JSON object indicating whether the domain has A records (IPv4) and/or AAAA records (IPv6), the actual DNS records including IP addresses and TTL values, and metadata about the source (Cloudflare DoH). Includes hasA and hasAAAA boolean flags for quick liveness checks.

## 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",
     "required": [
      "domain"
     ],
     "properties": {
      "domain": {
       "type": "string",
       "description": "Hostname (no scheme)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "hasA": true,
  "note": "DNS A/AAAA via Cloudflare DoH; not WHOIS or full DNSSEC audit",
  "domain": "example.com",
  "source": "cloudflare-doh",
  "hasAAAA": false,
  "records": [
   {
    "ttl": 300,
    "data": "93.184.216.34",
    "type": "A"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/payload402-dns-liveness-lookup-653673d1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from payload402.edgebytenet.workers.dev](https://www.zero.xyz/host/payload402.edgebytenet.workers.dev/llms.txt)