Apex domains cannot have CNAME records.
Question and response
Question
dig CA. NS
Answer
ca. 2 NS j.ca-servers.CA.
ca. 2 NS c.ca-servers.CA.
ca. 2 NS d.ca-servers.CA.
ca. 2 NS any.ca-servers.CA.
Authority
The response has no authority records.
Additional
c.ca-servers.ca. 112713 A 185.159.196.2
d.ca-servers.ca. 167922 A 45.142.220.101
j.ca-servers.ca. 127137 A 198.182.167.1
any.ca-servers.ca. 92688 A 199.4.144.2
c.ca-servers.ca. 112713 AAAA 2620:10a:8053:0:0:0:0:2
d.ca-servers.ca. 167922 AAAA 2a0e:dbc0:0:0:0:0:0:101
j.ca-servers.ca. 127137 AAAA 2001:500:83:0:0:0:0:1
any.ca-servers.ca. 92688 AAAA 2001:500:a7:0:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0