Apex domains cannot have CNAME records.
Question and response
Question
dig cecosa.com.ar. NS
Answer
cecosa.com.ar. 5 NS ns362.dnsever.com.
cecosa.com.ar. 5 NS ns352.dnsever.com.
cecosa.com.ar. 5 NS ns325.dnsever.com.
cecosa.com.ar. 5 NS ns391.dnsever.com.
cecosa.com.ar. 5 NS ns303.dnsever.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0