CNAME record
A DNS alias — points one hostname at another rather than at an IP. Useful for delegating subdomains to managed services (e.g. www.example.com → cdn.fastly.net).
Restrictions
A CNAME can’t coexist with other records at the same name (RFC 1034). That’s why apex domains (example.com itself) usually need ALIAS or ANAME pseudo-records instead — a true CNAME at the apex breaks the spec.
Common use
Pointing a custom domain at SaaS — Cloudflare, Heroku, Vercel — almost always works through a CNAME on a subdomain (www, app, api).