Apex domains cannot have CNAME records.
Question and response
Question
dig adc.net.ar. NS
Answer
adc.net.ar. 3 NS ns2.adc.net.ar.
adc.net.ar. 3 NS ns3.adc.net.ar.
adc.net.ar. 3 NS ns1.adc.net.ar.
Authority
The response has no authority records.
Additional
ns1.adc.net.ar. 3 A 181.174.152.131
ns2.adc.net.ar. 3 A 190.105.178.74
ns3.adc.net.ar. 3 A 181.174.152.130
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0