Apex domains cannot have CNAME records.
Question and response
Question
dig atom.com. NS
Answer
atom.com. 3 NS kayleigh.ns.cloudflare.com.
atom.com. 3 NS frank.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0