Apex domains cannot have CNAME records.
Question and response
Question
dig ms.uncu.edu.ar. NS
Answer
ms.uncu.edu.ar. 3 NS ns2.ms.uncu.edu.ar.
ms.uncu.edu.ar. 3 NS zonda.uncu.edu.ar.
ms.uncu.edu.ar. 3 NS ns1.ms.uncu.edu.ar.
Authority
The response has no authority records.
Additional
ns1.ms.uncu.edu.ar. 3 A 200.9.147.34
ns2.ms.uncu.edu.ar. 3 A 170.210.2.97
zonda.uncu.edu.ar. 1 A 170.210.45.117
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0