CNAME Lookup

About CNAME Records

A CNAME (Canonical Name) record maps one domain name to another — the canonical name. When a DNS resolver looks up a CNAME, it follows the chain to the target and resolves that instead. CNAMEs are commonly used to point subdomains at CDN hostnames, load balancers, or platform providers without needing to know or update the underlying IP address.

How CNAME resolution works

When you visit www.example.com and it has a CNAME pointing to myapp.cdn.net, the resolver looks up the A record for myapp.cdn.net and returns that IP to the client. The CNAME indirection is transparent to end users but visible in DNS lookups.

CNAME restrictions

• Zone apex restriction — A CNAME cannot be placed at the root of a domain (the apex, e.g. example.com with no subdomain). This is because the apex must have an SOA and NS record, which cannot coexist with a CNAME. Some DNS providers offer "ALIAS" or "ANAME" records as a workaround.
• No coexistence with other record types — A CNAME cannot coexist with any other record type at the same name. You cannot have both a CNAME and an MX record at www.example.com.
• Chaining — CNAMEs can point to other CNAMEs, but this creates extra round-trips and is generally discouraged. Some resolvers limit chain depth.

Common CNAME use cases

• www.example.com → CDN hostname (e.g. Cloudflare, Akamai)
• mail.example.com → Mail provider hostname
• shop.example.com → Shopify or WooCommerce hostname
• docs.example.com → Notion, GitBook, or documentation platform hostname