📚 DNS Record Explainer
Reference guide for common DNS record types and their uses.
A Record
IPv4 Address
Purpose: Maps a domain name to an IPv4 address.
Example:
example.com. 3600 IN A 192.0.2.1 Use Cases:
- Point domain to web server
- Direct traffic to specific IPv4
AAAA Record
IPv6 Address
Purpose: Maps a domain name to an IPv6 address.
Example:
example.com. 3600 IN AAAA 2001:db8::1 Use Cases:
- Modern IPv6 connectivity
- Future-proof addressing
CNAME Record
Canonical Name
Purpose: Creates an alias from one domain to another.
Example:
www.example.com. 3600 IN CNAME example.com. Use Cases:
- Alias www to root domain
- Point to CDN or load balancer
MX Record
Mail Exchange
Purpose: Specifies mail servers for email delivery.
Example:
example.com. 3600 IN MX 10 mail.example.com. Use Cases:
- Configure email routing
- Priority-based mail delivery
TXT Record
Text
Purpose: Stores arbitrary text data.
Example:
example.com. 3600 IN TXT "v=spf1 include:_spf.google.com ~all" Use Cases:
- SPF email authentication
- Domain verification
- DKIM keys
NS Record
Name Server
Purpose: Delegates a zone to authoritative nameservers.
Example:
example.com. 3600 IN NS ns1.example.com. Use Cases:
- Delegate subdomain
- Specify DNS servers
SOA Record
Start of Authority
Purpose: Contains admin info about the zone.
Example:
example.com. 3600 IN SOA ns1.example.com. admin.example.com. (...) Use Cases:
- Zone configuration
- Serial number tracking
PTR Record
Pointer
Purpose: Reverse DNS lookup (IP to domain).
Example:
1.2.0.192.in-addr.arpa. 3600 IN PTR example.com. Use Cases:
- Reverse DNS verification
- Email server reputation
SRV Record
Service
Purpose: Specifies location of services.
Example:
_http._tcp.example.com. 3600 IN SRV 10 60 80 server.example.com. Use Cases:
- Service discovery
- Load balancing
CAA Record
Certification Authority Authorization
Purpose: Specifies which CAs can issue certificates.
Example:
example.com. 3600 IN CAA 0 issue "letsencrypt.org" Use Cases:
- SSL/TLS security
- Certificate control
Common TTL Values
| TTL (seconds) | Duration | Use Case |
|---|---|---|
| 60 | 1 minute | Testing, frequent changes |
| 300 | 5 minutes | Dynamic content |
| 3600 | 1 hour | Standard (recommended) |
| 86400 | 24 hours | Stable domains |