Apex domains cannot have CNAME records.
Question and response
Question
dig nic.net.mx. NS
Answer
nic.net.mx. 4 NS c.nic.mx.
nic.net.mx. 4 NS a.nic.mx.
nic.net.mx. 4 NS b.nic.mx.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0