Apex domains cannot have CNAME records.
Question and response
Question
dig dnw.cl. NS
Answer
dnw.cl. 5 NS dns2.dnw.cl.
dnw.cl. 5 NS dns1.dnw.cl.
Authority
The response has no authority records.
Additional
dns1.dnw.cl. 5 A 131.72.236.3
dns2.dnw.cl. 5 A 131.72.236.3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0