Look Up a CNAME Record
Trace where a subdomain actually points.
How to use it
- Enter the full subdomain, such as www.example.com.
- Press Check.
- If nothing is returned, the name points straight to an IP via an A record instead.
A CNAME makes one name point to another name rather than straight to an IP address. It's used constantly with subdomains: www pointing at the root domain, or a subdomain pointing at an external service like a store or a support platform.
The rule people most often break: you can't put a CNAME on the root domain itself if it carries other records such as MX — and the result is broken email. If you need that, use what your provider calls ALIAS, ANAME or CNAME flattening.
Frequently asked questions
Because the standard doesn't allow it when the domain carries other records. Root domains use an A record; CNAMEs normally live on subdomains.
Each extra hop is another DNS query and more delay before the page opens. One or two is fine; beyond that you're slowing the site for no benefit.
It does if placed on the root domain, because it conflicts with MX records and breaks delivery. On subdomains it has no effect on mail.