Apex domains cannot have CNAME records.
Question and response
Question
dig calacoop.com.ar. NS
Answer
calacoop.com.ar. 5 NS ns1.calacoop.com.ar.
Authority
The response has no authority records.
Additional
ns1.calacoop.com.ar. 5 A 179.0.224.42
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0