Apex domains cannot have CNAME records.
Question and response
Question
dig sitsanetworks.net. NS
Answer
sitsanetworks.net. 5 NS ns2.lzsnet.com.ar.
sitsanetworks.net. 5 NS ns1.lzsnet.com.ar.
Authority
The response has no authority records.
Additional
ns1.lzsnet.com.ar. 5 A 201.234.30.66
ns2.lzsnet.com.ar. 5 A 201.234.30.67
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0