Apex domains cannot have CNAME records.
Question and response
Question
dig utn.edu.ar. NS
Answer
utn.edu.ar. 5 NS ns1.utn.edu.ar.
utn.edu.ar. 5 NS ns1.riu.edu.ar.
utn.edu.ar. 5 NS ns3.utn.edu.ar.
utn.edu.ar. 5 NS ns2.utn.edu.ar.
Authority
The response has no authority records.
Additional
ns1.utn.edu.ar. 5 A 13.68.252.44
ns2.utn.edu.ar. 5 A 190.114.220.1
ns3.utn.edu.ar. 5 A 190.114.221.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0