DNS Server

A comprehensive DNS query server built with FastMCP that provides tools to query all types of DNS records and gather complete domain information.

Features

DNS Record Query Tools

• A Records - Query IPv4 addresses
• AAAA Records - Query IPv6 addresses
• MX Records - Query mail exchange servers with priorities
• TXT Records - Query text records (SPF, DKIM, DMARC, verification)
• NS Records - Query authoritative nameservers
• CNAME Records - Query canonical name aliases
• SOA Records - Query Start of Authority information
• PTR Records - Reverse DNS lookups
• SRV Records - Query service location records
• CAA Records - Query Certificate Authority Authorization
• DS/DNSKEY Records - Check DNSSEC configuration

Advanced Tools

• Query All Records - Get all DNS records for a domain in one call
• DNSSEC Check - Verify DNSSEC configuration
• WHOIS-style Lookup - Comprehensive domain information via DNS
• Domain Availability Check - Check if domain has DNS configured
• DNS Delegation Trace - Trace delegation chain from root to authoritative nameservers

Installation

Local Development

1. Install dependencies:

pip install -r requirements.txt

2. Run the server locally:

python dns_server.py

The server will start on http://localhost:8000 by default.

Deploy to FastMCP Cloud

1. Install FastMCP CLI if you haven't already:

pip install fastmcp

2. Login to FastMCP Cloud:

fastmcp login

3. Deploy the server:

fastmcp deploy dns_server.py

4. The CLI will provide you with a public URL where your MCP server is accessible.

Usage Examples

Using with MCP Client

import asyncio
from fastmcp import Client

# Replace with your deployed URL
client = Client("https://your-server.fastmcp.app/mcp")

async def main():
    async with client:
        # Query A records
        result = await client.call_tool("query_a_record", {"domain": "google.com"})
        print(result)
        
        # Query all records
        result = await client.call_tool("query_all_records", {"domain": "example.com"})
        print(result)
        
        # Reverse DNS lookup
        result = await client.call_tool("query_ptr_record", {"ip_address": "8.8.8.8"})
        print(result)
        
        # Check DNSSEC
        result = await client.call_tool("check_dnssec", {"domain": "cloudflare.com"})
        print(result)

asyncio.run(main())

Available Tools

Basic DNS Queries

• query_a_record(domain: str) - Get IPv4 addresses
• query_aaaa_record(domain: str) - Get IPv6 addresses
• query_mx_record(domain: str) - Get mail servers
• query_txt_record(domain: str) - Get TXT records
• query_ns_record(domain: str) - Get nameservers
• query_cname_record(domain: str) - Get CNAME alias
• query_soa_record(domain: str) - Get SOA information
• query_caa_record(domain: str) - Get CAA records

Advanced Queries

• query_ptr_record(ip_address: str) - Reverse DNS lookup
• query_srv_record(service: str, protocol: str, domain: str) - Service location
• query_all_records(domain: str) - Get all DNS records at once
• check_dnssec(domain: str) - Check DNSSEC status
• whois_lookup(domain: str) - Comprehensive domain info
• check_domain_availability(domain: str) - Check if domain is configured
• trace_dns_delegation(domain: str) - Trace delegation chain

DNS Resolver Configuration

The server uses the following public DNS resolvers:

• Google DNS: 8.8.8.8, 8.8.4.4
• Cloudflare DNS: 1.1.1.1

Timeout: 5 seconds Lifetime: 10 seconds

Response Format

All tools return structured JSON responses with:

• success: Boolean indicating if query succeeded
• domain/ip_address: The queried domain or IP
• record_type: Type of DNS record
• records: Array of record data with TTL information
• nameserver: The nameserver that provided the response
• error: Error message if query failed

Example Response

{
  "domain": "example.com",
  "record_type": "A",
  "records": [
    {
      "data": "93.184.216.34",
      "ttl": 86400,
      "type": "A"
    }
  ],
  "nameserver": "8.8.8.8",
  "success": true
}

Use Cases

• Domain Investigation - Research domain DNS configuration
• Email Configuration - Check MX and SPF/DKIM/DMARC records
• Security Analysis - Verify DNSSEC, CAA records
• Network Troubleshooting - Reverse lookups, delegation tracing
• Domain Monitoring - Track DNS changes and availability
• Migration Planning - Document current DNS setup

Error Handling

The server gracefully handles DNS query failures and returns structured error responses:

{
  "domain": "nonexistent.example",
  "record_type": "A",
  "error": "The DNS query name does not exist: nonexistent.example.",
  "success": false
}

License

MIT License

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.