# DNS name length checker

- Human page: https://happytails.ai/en/developer-tools/dns-name-length-checker/
- Markdown: https://happytails.ai/en/developer-tools/dns-name-length-checker.md
- Structured JSON: https://happytails.ai/agents/en/developer-tools/dns-name-length-checker/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `dns-name-length-checker` |
| Category | developer-tools |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Use the visible action or interactive controls. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | Not callable through HTTP. |
| Browser-agent interface | run_current_tool |

### Implementation notes

Paste one DNS name per line. Labels are measured in UTF-8 bytes against 63-octet limits and the absolute wire name against 255 octets. IDNA conversion is not performed. Process up to 500000 input characters and 20000 records locally. Reports and source text export completely, capped at 40 million characters and 500000 CSV records. Previews show the first 200 rows; analysis stops after 10 seconds. No data is uploaded.

### Inputs and settings

Text input: Your text.

Example or placeholder shown in the interface (not a validated fixture):

```text
Type or paste your input…
```

Up to 500,000 characters. Review the settings before running.

No additional settings are declared for this tool.

### Browser-agent workflow

1. Open the human page in a browser that supports WebMCP.
2. Discover the interface exposed by that page; use its actual schema.
3. Select files on the page first when the tool requires files.
4. Call `run_current_tool` with valid input and settings.
5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.

Calls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.

### Planning specification

Process up to 500000 input characters and 20000 records locally. Reports export completely up to 40 million characters and 500000 CSV records. Analysis is local with a 10-second timeout. Preview tables show the first 200 rows; your data is not uploaded.

This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.

### Complete machine-readable capability record

```json
{
  "id": "dns-name-length-checker",
  "category": "developer-tools",
  "built": true,
  "requirements": "Process up to 500000 input characters and 20000 records locally. Reports export completely up to 40 million characters and 500000 CSV records. Analysis is local with a 10-second timeout. Preview tables show the first 200 rows; your data is not uploaded.",
  "implementation": {
    "fields": [],
    "presentation": "metrics",
    "inputMaxLength": 500000,
    "inputErrorCode": "NETWORK_DIAGNOSTICS_INPUT",
    "note": "Paste one DNS name per line. Labels are measured in UTF-8 bytes against 63-octet limits and the absolute wire name against 255 octets. IDNA conversion is not performed. Process up to 500000 input characters and 20000 records locally. Reports and source text export completely, capped at 40 million characters and 500000 CSV records. Previews show the first 200 rows; analysis stops after 10 seconds. No data is uploaded.",
    "example": {
      "input": "example.com\nvery-long-label.example.",
      "options": {}
    },
    "experience": {
      "automatic": false,
      "single": false,
      "inputMaxLength": 500000,
      "inputMode": "text",
      "label": "Your text",
      "placeholder": "Type or paste your input…",
      "help": "Up to 500,000 characters. Review the settings before running.",
      "action": null
    },
    "mode": "explicit",
    "interactive": false
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}
```

## Page guide

Paste one DNS name per line.

How can we improve this tool?

Report a problem or share an idea.

Please leave out private information. Your message and the tool name go to our team via PostHog.

### How to use DNS name length checker

1. Paste text or JSON in the documented format.
2. Review the bounded report and explicit assumptions.
3. Download complete JSON or CSV.

## Useful next steps

- [DNS zone diff](https://happytails.ai/en/developer-tools/dns-zone-diff/) ([Markdown](https://happytails.ai/en/developer-tools/dns-zone-diff.md))

- [HTTP cache policy analyzer](https://happytails.ai/en/developer-tools/http-cache-policy-analyzer/) ([Markdown](https://happytails.ai/en/developer-tools/http-cache-policy-analyzer.md))

- [IP allowlist overlap checker](https://happytails.ai/en/developer-tools/ip-allowlist-overlap-checker/) ([Markdown](https://happytails.ai/en/developer-tools/ip-allowlist-overlap-checker.md))

## Know the interpretation limits

Paste one DNS name per line. Labels are measured in UTF-8 bytes against 63-octet limits and the absolute wire name against 255 octets. IDNA conversion is not performed.

### Keep the complete report

Search and sort apply to the first 200 rows. Download JSON or CSV for every row and the assumptions.