Apex domains cannot have CNAME records.
Question and response
Question
dig blacom.com.mx. NS
Answer
blacom.com.mx. 4 NS dns1.internetcomunicate.mx.
Authority
The response has no authority records.
Additional
dns1.internetcomunicate.mx. 4 A 201.131.200.14
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0