http://blog.cloudflare.com/introducing-cname-flattening-rfc-compliant-cnames-at-a-domains-root/ http://blog.cloudflare.com/introducing-cname-flattening-rfc-...

http://blog.cloudflare.com/introducing-cname-flattening-rfc-compliant-cnames-at-a-domains-root/ http://blog.cloudflare.com/introducing-cname-flattening-rfc-... is a reasonable explanation. fundamentally a CNAME says "when you get queries for this name, go look at this other name instead". among other things, doing a CNAME at the zone apex means resolvers can't then find your NS, MX, or other records at the apex, which is problematic.