Apex domains cannot have CNAME records.
Question and response
Question
dig apotex.com.mx. NS
Answer
apotex.com.mx. 5 NS abby.ns.cloudflare.com.
apotex.com.mx. 5 NS anderson.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0