A CNAME (canonical name) record declares that a hostname is an alias for another hostname. A resolver that finds a CNAME restarts the lookup at the target name and returns whatever records it finds there.
Why it matters
CNAMEs let you point www or shop at a provider such as a CDN, hosting platform or e-commerce service without tracking their IP addresses. When the provider changes servers, your site follows automatically. The trade-off is a hard rule: a name that has a CNAME cannot have any other record type at the same name, which is why a CNAME cannot sit at the zone apex, where SOA and NS records must live.
Example
www.example.com. 300 IN CNAME example.myshopify.com.dig www.example.com returns the CNAME followed by the A records of example.myshopify.com.
Common mistakes
- Putting a CNAME at the root domain. Use an ALIAS/ANAME or CNAME-flattening feature if your DNS host offers one.
- Adding a CNAME next to an existing MX or TXT record on the same name, which is invalid and behaves unpredictably.
- Pointing MX or NS records at a name that is itself a CNAME.
- Leaving a CNAME to a deprovisioned service, which opens a subdomain takeover.
Related
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