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