Glossary
DNS RECORDS

CNAME Record

Canonical Name record — maps a hostname to another hostname rather than an IP address. Used for aliases and pointing subdomains at external services.

A CNAME record (Canonical Name) creates an alias from one hostname to another. Instead of mapping to an IP address, it maps to another hostname which is then resolved normally.

Format

www.example.com.   3600  IN  CNAME  example.com.
shop.example.com.  3600  IN  CNAME  stores.myshopify.com.
blog.example.com.  3600  IN  CNAME  example.ghost.io.

When a resolver encounters a CNAME, it follows the chain until it finds an A or AAAA record.

Rules

  • Cannot be used at the domain apex (example.com / @). Only allowed on subdomains.
  • Cannot coexist with other record types at the same name — no CNAME + MX at the same hostname.
  • Can chain but more than 3 hops slows resolution.

CNAME Flattening (ALIAS)

Some DNS providers offer CNAME-like behavior at the apex: Cloudflare (CNAME Flattening), AWS Route 53 (ALIAS), and DNSimple (ALIAS). These resolve the target and return an A record, making it appear as an A record to clients.

Common Use Cases

  • Pointing www. to the root domain
  • Pointing a subdomain to a CDN, SaaS, or load balancer whose IP changes
  • Keeping multiple subdomains synchronized — update the target’s A record and all CNAMEs update automatically
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