Why I get error when fit with `@` in Host?
I want to add a @ CNAME points to an alias in Godaddy.
You see I write @ in Host, but it still say I was wrong.
I am unfamiliar with this particular control panel layout, but it seems to me you misunderstand hiw CNAMES work (a common misconception)
A CNAME is not an alias, it redelegates authority for that and all subdomains and records at the same level (including NS records).
The take-away is you can only use CNAMES on subdomains.
A CNAME for www.example.com is OK but example.com is not.