Apex domains cannot have CNAME records.
Question and response
Question
dig net.mx. NS
Answer
net.mx. 5 NS e.mx-ns.mx.
net.mx. 5 NS m.mx-ns.mx.
net.mx. 5 NS x.mx-ns.mx.
net.mx. 5 NS o.mx-ns.mx.
net.mx. 5 NS i.mx-ns.mx.
net.mx. 5 NS c.mx-ns.mx.
Authority
The response has no authority records.
Additional
c.mx-ns.mx. 31571 A 192.100.224.1
e.mx-ns.mx. 31571 A 189.201.244.1
i.mx-ns.mx. 31571 A 207.248.68.1
m.mx-ns.mx. 119090 A 200.94.176.1
o.mx-ns.mx. 31571 A 200.23.1.1
x.mx-ns.mx. 31571 A 201.131.252.1
c.mx-ns.mx. 31571 AAAA 2001:1258:0:0:0:0:0:1
e.mx-ns.mx. 31571 AAAA 2801:c4:c0:0:0:0:0:1
i.mx-ns.mx. 31571 AAAA 2801:c4:d0:0:0:0:0:1
m.mx-ns.mx. 119090 AAAA 2001:13c7:7000:0:0:0:0:1
o.mx-ns.mx. 31571 AAAA 2001:1201:0:0:0:0:0:1
x.mx-ns.mx. 31571 AAAA 2001:1201:10:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0