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