MagicDNS & DNS Configuration Standards

This rule applies to files matching the patterns above.

# MagicDNS & DNS Configuration Standards

## Rule
All Tailscale networks MUST use MagicDNS for service discovery. Never use raw Tailscale IP addresses in configuration files or code.

## Format
```
{hostname}.{tailnet-name}.ts.net
```

## Rules
1. ALWAYS use MagicDNS names, never 100.x.y.z IP addresses
2. Use descriptive hostnames matching device function
3. Configure split DNS for internal domain routing
4. Set global nameservers for reliable DNS resolution
5. Use search domains for shortened names

## Device Naming for MagicDNS
```bash
# Set descriptive hostname
tailscale up --hostname=api-server-prod

# Accessible as:
# api-server-prod.your-tailnet.ts.net
# api-server-prod (with search domain configured)
```

## Split DNS Configuration
```json
{
  "dns": {
    "nameservers": ["1.1.1.1", "8.8.8.8"],
    "routes": {
      "internal.company.com": ["10.0.0.53"],
      "staging.company.com": ["10.0.1.53"]
    },
    "domains": ["your-tailnet.ts.net"]
  }
}
```

## Configuration Examples

### Good
```bash
# Using MagicDNS in configs
DATABASE_URL=postgresql://user:pass@db-primary.ts.net:5432/myapp
REDIS_URL=redis://cache-01.ts.net:6379
API_URL=https://api-server.ts.net:443
```

### Bad
```bash
# Hardcoded Tailscale IPs (breaks when devices change)
DATABASE_URL=postgresql://user:pass@100.64.0.5:5432/myapp
REDIS_URL=redis://100.64.0.12:6379
```

## Enforcement
Grep for 100.x.y.z patterns in configuration files.
Use MagicDNS names in all documentation.
Verify DNS resolution works before deploying configurations.