Apex domains cannot have CNAME records.
Question and response
Question
dig unl.edu.ar. NS
Answer
unl.edu.ar. 4 NS dns2.unl.edu.ar.
unl.edu.ar. 4 NS dns4.unl.edu.ar.
unl.edu.ar. 4 NS dns1.unl.edu.ar.
unl.edu.ar. 4 NS dns3.unl.edu.ar.
Authority
The response has no authority records.
Additional
dns1.unl.edu.ar. 4 A 190.122.240.12
dns2.unl.edu.ar. 4 A 190.122.252.12
dns3.unl.edu.ar. 4 A 190.122.253.12
dns4.unl.edu.ar. 4 A 190.122.254.12
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0