# ASCII DNS Hostname Validator

> ASCII DNS Hostname Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-19).

Checks whether a given string is a valid ASCII DNS hostname (no Unicode labels).

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-hostname?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ascii-dns-hostname-validator-6610a3a7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_eHwnjXqBq11Q_ZY4jEazj

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 ascii-dns-hostname-validator-6610a3a7 -d '<json body>'
```

Example prompt: Can you check whether 'mail.example-corp.com' is a valid ASCII DNS hostname?

## When to prefer this

Use this endpoint when you need strict ASCII-only hostname validation (rejecting Unicode/IDN labels) and have already exhausted the free sandbox quota at POST /v1/sandbox/check-hostname. Prefer this over the Unicode hostname endpoint when your use case requires pure ASCII compliance (e.g. legacy DNS systems, email routing, configuration validation).

## Known failure modes

- Empty string input rejected (minLength:1 constraint)
- String exceeding 20000 characters rejected (maxLength constraint)
- Payment failure results in 402 response — consider using the free sandbox endpoint first
- Malformed request body returns an error
- Non-string value for 'value' field causes schema validation error

## How this service works

Call when an agent needs whether a string is an ASCII DNS hostname. Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/check-hostname first.

## Output

A boolean or pass/fail result indicating whether the provided string conforms to ASCII DNS hostname rules (no Unicode/IDN labels, valid label structure and characters).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."
  },
  "value": {
   "type": "string",
   "examples": [
    "example.com"
   ],
   "maxLength": 20000,
   "minLength": 1,
   "description": "Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."
  },
  "schema": {
   "description": "JSON Schema document for schema-check SKUs. Omit it on string checks."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ascii-dns-hostname-validator-6610a3a7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)