Is it possible to set a CNAME record at the top of a domain? (i.e. @ CNAME www
, @ CNAME foobar.com.
, etc.)
My ISP says that it's only possible to use CNAME's for subdomains but I've read somewhere else that is should be possible even if not recommended.
Not possible - this would conflict with the SOA- and NS-records at the domain root.
From RFC1912 section 2.4: "A CNAME record is not allowed to coexist with any other data."
You can setup your domain to be a CNAME to another domain, but then everything will go to that other domain -- including mail and the SOA "start-of-authority" record itself. However, you can still have separate subdomains, like "private.domain.com" use another mail and web server.
I use cloudflare to setup CNAME for root domain and it works fine.. without breaking the mail records