What is a CNAME record?

A CNAME (Canonical Name) record says "this hostname is just another name for that hostname." When a resolver queries the alias, the DNS server returns the CNAME target, and the resolver follows it, possibly through more CNAMEs, until it finds an A or AAAA record with the actual IP.

CNAMEs are how SaaS products give you a custom domain. You point app.yourbrand.com to a CNAME like cname.vercel-dns.com or proxy.cloudflare.com, and the provider's infrastructure handles the rest, including issuing TLS certificates for your domain.

There's one important rule: a CNAME cannot coexist with other records on the same name, which is why you can't put a CNAME on the apex (root) of a domain in standard DNS. Most providers offer "CNAME flattening" or "ALIAS" records as a workaround.