managing-dns

# DNS Management

Configure and automate DNS records with proper TTL strategies, DNS-as-code patterns, and troubleshooting techniques.

## Purpose

Guide DNS configuration for applications, infrastructure, and services with focus on:
- Record type selection (A, AAAA, CNAME, MX, TXT, SRV, CAA)
- TTL strategies for propagation and caching
- DNS-as-code automation (external-dns, OctoDNS, DNSControl)
- Cloud DNS services comparison and selection
- DNS-based load balancing patterns
- Troubleshooting tools and techniques

## When to Use This Skill

Apply DNS management patterns when:
- Setting up DNS for new applications or services
- Automating DNS updates from Kubernetes workloads
- Configuring DNS-based failover or load balancing
- Troubleshooting DNS propagation or resolution issues
- Migrating DNS between providers
- Planning DNS changes with minimal downtime
- Implementing GeoDNS for global users

## Record Type Selection

### Quick Reference

**Address Resolution:**
- **A Record**: Map hostname to IPv4 address (example.com → 192.0.2.1)
- **AAAA Record**: Map hostname to IPv6 address (example.com → 2001:db8::1)
- **CNAME Record**: Alias to another domain (www.example.com → example.com)
  - Cannot use at zone apex (@)
  - Cannot coexist with other records at same name

**Email Configuration:**
- **MX Record**: Direct email to mail servers with priority
- **TXT Record**: Email authentication (SPF, DKIM, DMARC) and verification

**Service Discovery:**
- **SRV Record**: Specify service location (protocol, priority, weight, port, target)

**Delegation and Security:**
- **NS Record**: Delegate subdomain to different nameservers
- **CAA Record**: Restrict which Certificate Authorities can issue certificates

**Cloud-Specific:**
- **ALIAS Record**: Like CNAME but works at zone apex (Route53, Cloudflare)

### Decision Tree

```
Need to point domain to:
├─ IPv4 Address? → A record
├─ IPv6 Address? → AAAA record
├─ Another Domain?
│  ├─ Zone apex (@) → ALIAS/ANAME or A record