mcp-dns

Model Context Protocol server for DNS lookups — gives AI agents two tools: resolve_dns (A, AAAA, CNAME, MX, TXT, NS, SOA, SRV, CAA) and reverse_dns (PTR). Built on node:dns only: no external APIs, no keys, no telemetry.

Playground

No install needed — try live DNS lookups in the browser at https://yeeeeezus.github.io/mcp-dns/ (DNS-over-HTTPS queries go straight from your browser to Google Public DNS). The server below is the same idea for AI agents.

Related MCP server: MCP Cloudflare DNS Server

Why

Agents doing web work, security review, infrastructure debugging or mail deliverability checks constantly need DNS facts: where does this domain point, what are its nameservers, does it have SPF/DMARC records, what does this IP reverse to. Instead of hoping the model remembers a shell one-liner, give it typed tools that return structured answers over the MCP stdio transport.

Tools

resolve_dns

For SRV, pass the full query name (e.g. _xmpp-server._tcp.gmail.com).

reverse_dns

Example exchange

Request:

{ "name": "resolve_dns", "arguments": { "domain": "gmail.com", "recordType": "MX" } }

Response:

[
  { "exchange": "gmail-smtp-in.l.google.com", "priority": 5, "type": "MX" },
  { "exchange": "alt1.gmail-smtp-in.l.google.com", "priority": 10, "type": "MX" },
  { "exchange": "alt2.gmail-smtp-in.l.google.com", "priority": 20, "type": "MX" },
  { "exchange": "alt3.gmail-smtp-in.l.google.com", "priority": 30, "type": "MX" },
  { "exchange": "alt4.gmail-smtp-in.l.google.com", "priority": 40, "type": "MX" }
]

Install

Run directly without cloning:

$ npx github:yeeeeezus/mcp-dns

or from a checkout:

$ git clone https://github.com/yeeeeezus/mcp-dns
$ cd mcp-dns && npm install && npm run build
$ node dist/index.js

Claude Desktop / any MCP client

{
  "mcpServers": {
    "mcp-dns": {
      "command": "npx",
      "args": ["github:yeeeeezus/mcp-dns"]
    }
  }
}

Behavior notes

• ENOTFOUND / ENODATA are mapped to clean tool errors ("no MX records found for …") instead of stack traces.

• Hostnames are validated before resolution; URLs and paths are rejected up front.

• TXT record chunks are joined into single strings (the DNS wire format splits long TXT values).

• Output is pretty-printed JSON text, one record set per call.

Development

$ npm install
$ npm test

8 tests, including a full integration test that spawns the built server and speaks MCP JSON-RPC over stdio: initialize handshake, tools/list, two real tools/call resolutions, and an error-path check.

License

MIT