Apex domains cannot have CNAME records.
Question and response
Question
dig COM. NS
Answer
COM. 5 NS b.gtld-servers.net.
COM. 5 NS k.gtld-servers.net.
COM. 5 NS f.gtld-servers.net.
COM. 5 NS a.gtld-servers.net.
COM. 5 NS e.gtld-servers.net.
COM. 5 NS d.gtld-servers.net.
COM. 5 NS h.gtld-servers.net.
COM. 5 NS c.gtld-servers.net.
COM. 5 NS g.gtld-servers.net.
COM. 5 NS i.gtld-servers.net.
COM. 5 NS j.gtld-servers.net.
COM. 5 NS m.gtld-servers.net.
COM. 5 NS l.gtld-servers.net.
Authority
The response has no authority records.
Additional
a.gtld-servers.net. 160495 A 192.5.6.30
b.gtld-servers.net. 160351 A 192.33.14.30
c.gtld-servers.net. 134990 A 192.26.92.30
d.gtld-servers.net. 123901 A 192.31.80.30
e.gtld-servers.net. 161080 A 192.12.94.30
f.gtld-servers.net. 160659 A 192.35.51.30
g.gtld-servers.net. 139558 A 192.42.93.30
h.gtld-servers.net. 160311 A 192.54.112.30
i.gtld-servers.net. 160404 A 192.43.172.30
j.gtld-servers.net. 159252 A 192.48.79.30
k.gtld-servers.net. 160622 A 192.52.178.30
l.gtld-servers.net. 160167 A 192.41.162.30
m.gtld-servers.net. 160198 A 192.55.83.30
a.gtld-servers.net. 160495 AAAA 2001:503:a83e:0:0:0:2:30
b.gtld-servers.net. 160351 AAAA 2001:503:231d:0:0:0:2:30
c.gtld-servers.net. 134990 AAAA 2001:503:83eb:0:0:0:0:30
d.gtld-servers.net. 123901 AAAA 2001:500:856e:0:0:0:0:30
e.gtld-servers.net. 161080 AAAA 2001:502:1ca1:0:0:0:0:30
f.gtld-servers.net. 160659 AAAA 2001:503:d414:0:0:0:0:30
g.gtld-servers.net. 139558 AAAA 2001:503:eea3:0:0:0:0:30
h.gtld-servers.net. 160311 AAAA 2001:502:8cc:0:0:0:0:30
i.gtld-servers.net. 160404 AAAA 2001:503:39c1:0:0:0:0:30
j.gtld-servers.net. 159252 AAAA 2001:502:7094:0:0:0:0:30
k.gtld-servers.net. 160622 AAAA 2001:503:d2d:0:0:0:0:30
l.gtld-servers.net. 160167 AAAA 2001:500:d937:0:0:0:0:30
m.gtld-servers.net. 160198 AAAA 2001:501:b1f9:0:0:0:0:30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0