Apex domains cannot have CNAME records.
Question and response
Question
dig AR. NS
Answer
ar. 1 NS f.dns.ar.
ar. 1 NS e.dns.ar.
ar. 1 NS d.dns.ar.
ar. 1 NS c.dns.ar.
ar. 1 NS a.lactld.org.
Authority
The response has no authority records.
Additional
a.lactld.org. 1 A 200.0.68.10
c.dns.AR. 118693 A 200.108.148.50
d.dns.AR. 164047 A 192.140.126.50
e.dns.AR. 162278 A 170.238.66.50
f.dns.AR. 167484 A 130.59.31.20
a.lactld.org. 1 AAAA 2801:14:a000:0:0:0:0:10
c.dns.AR. 118693 AAAA 2801:140:10:0:0:0:0:10
d.dns.AR. 164047 AAAA 2801:140:dddd:0:0:0:0:50
e.dns.AR. 162278 AAAA 2801:140:eeee:0:0:0:0:50
f.dns.AR. 167484 AAAA 2001:620:0:ff:0:0:0:20
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0