Apex domains cannot have CNAME records.
Question and response
Question
dig promohosts.com. NS
Answer
promohosts.com. 5 NS ned.ns.cloudflare.com.
promohosts.com. 5 NS ingrid.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0