Apex domains cannot have CNAME records.
Question and response
Question
dig net. NS
Answer
net. 2 NS j.gtld-servers.net.
net. 2 NS e.gtld-servers.net.
net. 2 NS a.gtld-servers.net.
net. 2 NS g.gtld-servers.net.
net. 2 NS b.gtld-servers.net.
net. 2 NS m.gtld-servers.net.
net. 2 NS k.gtld-servers.net.
net. 2 NS d.gtld-servers.net.
net. 2 NS l.gtld-servers.net.
net. 2 NS f.gtld-servers.net.
net. 2 NS h.gtld-servers.net.
net. 2 NS c.gtld-servers.net.
net. 2 NS i.gtld-servers.net.
Authority
The response has no authority records.
Additional
a.gtld-servers.net. 83591 A 192.5.6.30
b.gtld-servers.net. 64864 A 192.33.14.30
c.gtld-servers.net. 49557 A 192.26.92.30
d.gtld-servers.net. 131094 A 192.31.80.30
e.gtld-servers.net. 49557 A 192.12.94.30
f.gtld-servers.net. 49557 A 192.35.51.30
g.gtld-servers.net. 171930 A 192.42.93.30
h.gtld-servers.net. 49557 A 192.54.112.30
i.gtld-servers.net. 49557 A 192.43.172.30
j.gtld-servers.net. 88654 A 192.48.79.30
k.gtld-servers.net. 122436 A 192.52.178.30
l.gtld-servers.net. 118238 A 192.41.162.30
m.gtld-servers.net. 49557 A 192.55.83.30
a.gtld-servers.net. 83591 AAAA 2001:503:a83e:0:0:0:2:30
b.gtld-servers.net. 64864 AAAA 2001:503:231d:0:0:0:2:30
c.gtld-servers.net. 49557 AAAA 2001:503:83eb:0:0:0:0:30
d.gtld-servers.net. 131094 AAAA 2001:500:856e:0:0:0:0:30
e.gtld-servers.net. 49557 AAAA 2001:502:1ca1:0:0:0:0:30
f.gtld-servers.net. 49557 AAAA 2001:503:d414:0:0:0:0:30
g.gtld-servers.net. 171930 AAAA 2001:503:eea3:0:0:0:0:30
h.gtld-servers.net. 49557 AAAA 2001:502:8cc:0:0:0:0:30
i.gtld-servers.net. 49557 AAAA 2001:503:39c1:0:0:0:0:30
j.gtld-servers.net. 88654 AAAA 2001:502:7094:0:0:0:0:30
k.gtld-servers.net. 122436 AAAA 2001:503:d2d:0:0:0:0:30
l.gtld-servers.net. 118238 AAAA 2001:500:d937:0:0:0:0:30
m.gtld-servers.net. 49557 AAAA 2001:501:b1f9:0:0:0:0:30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0