Apex domains cannot have CNAME records.
Question and response
Question
dig wikipedia.org. NS
Answer
wikipedia.org. 1 NS ns0.wikimedia.org.
wikipedia.org. 1 NS ns1.wikimedia.org.
wikipedia.org. 1 NS ns2.wikimedia.org.
Authority
The response has no authority records.
Additional
ns0.wikimedia.org. 1 A 208.80.154.238
ns1.wikimedia.org. 1 A 208.80.153.231
ns2.wikimedia.org. 1 A 198.35.27.27
ns1.wikimedia.org. 1 AAAA 2620:0:860:53:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0