Apex domains cannot have CNAME records.
Question and response
Question
dig edu.ar. NS
Answer
edu.ar. 5 NS noc.uncu.edu.ar.
edu.ar. 5 NS a.riu.edu.ar.
edu.ar. 5 NS ns2.switch.ch.
edu.ar. 5 NS unlp.unlp.edu.ar.
edu.ar. 5 NS b.riu.edu.ar.
edu.ar. 5 NS ns1.uba.ar.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0