Apex domains cannot have CNAME records.
Question and response
Question
dig imeris.uncu.edu.ar. NS
Answer
imeris.uncu.edu.ar. 5 NS ns.fing.uncu.edu.ar.
Authority
The response has no authority records.
Additional
ns.fing.uncu.edu.ar. 5 A 200.12.134.130
ns.fing.uncu.edu.ar. 5 A 200.12.134.131
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0