{
  "category": "domains",
  "updated": "2026-10-08",
  "confidence_levels": {
    "verified": "Read on the official page/file.",
    "verified-archive": "Official page, read via a Wayback Machine snapshot (live site blocks automated fetches); 'archive' has the snapshot URL.",
    "secondary": "Secondary source only (e.g. Wikipedia); treat as unconfirmed.",
    "uncertain": "Plausible but not confirmed; do not rely on it."
  },
  "title": "Reserved domain names and TLDs",
  "note": "example.com/.net/.org resolve normally (RFC 6761 6.5) but are registered to IANA in perpetuity; today they publish a null MX and SPF -all, so mail to them is undeliverable. Use .test for test infrastructure, .invalid for names that must never resolve.",
  "items": [
    {
      "value": "example.com",
      "purpose": "Second-level domain reserved for documentation and examples",
      "source": "https://www.rfc-editor.org/rfc/rfc2606",
      "confidence": "verified"
    },
    {
      "value": "example.net",
      "purpose": "Second-level domain reserved for documentation and examples",
      "source": "https://www.rfc-editor.org/rfc/rfc2606",
      "confidence": "verified"
    },
    {
      "value": "example.org",
      "purpose": "Second-level domain reserved for documentation and examples",
      "source": "https://www.rfc-editor.org/rfc/rfc2606",
      "confidence": "verified"
    },
    {
      "value": ".example",
      "purpose": "TLD reserved for documentation and examples",
      "source": "https://www.rfc-editor.org/rfc/rfc2606",
      "confidence": "verified"
    },
    {
      "value": ".test",
      "purpose": "TLD for testing DNS-related code; caching/authoritative servers SHOULD answer negatively by default",
      "source": "https://www.rfc-editor.org/rfc/rfc6761",
      "confidence": "verified",
      "also": "https://www.rfc-editor.org/rfc/rfc2606"
    },
    {
      "value": ".invalid",
      "purpose": "TLD for names that are sure to be invalid; SHOULD get an immediate NXDOMAIN",
      "source": "https://www.rfc-editor.org/rfc/rfc6761",
      "confidence": "verified",
      "also": "https://www.rfc-editor.org/rfc/rfc2606"
    },
    {
      "value": ".localhost",
      "purpose": "Loopback names; resolvers SHOULD return loopback addresses and never forward",
      "source": "https://www.rfc-editor.org/rfc/rfc6761",
      "confidence": "verified",
      "also": "https://www.rfc-editor.org/rfc/rfc2606"
    },
    {
      "value": "home.arpa",
      "purpose": "Special-use name for residential home networks (replaces .home)",
      "source": "https://www.rfc-editor.org/rfc/rfc8375",
      "confidence": "verified"
    },
    {
      "value": ".alt",
      "purpose": "Special-use TLD for non-DNS (alternative) namespaces",
      "source": "https://www.rfc-editor.org/rfc/rfc9476",
      "confidence": "verified"
    },
    {
      "value": ".local",
      "purpose": "Multicast DNS (mDNS) link-local names - not for examples",
      "source": "https://www.rfc-editor.org/rfc/rfc6762",
      "confidence": "verified"
    },
    {
      "value": ".onion",
      "purpose": "Tor onion services - not for examples",
      "source": "https://www.rfc-editor.org/rfc/rfc7686",
      "confidence": "verified"
    },
    {
      "value": "IANA registry",
      "purpose": "Authoritative list of special-use domain names",
      "source": "https://www.iana.org/assignments/special-use-domain-names/",
      "confidence": "verified"
    }
  ]
}