Apex domains cannot have CNAME records.
Question and response
Question
dig cloudns.cl. NS
Answer
cloudns.cl. 2 NS ns104.cloudns.net.
cloudns.cl. 2 NS ns101.cloudns.net.
cloudns.cl. 2 NS ns102.cloudns.net.
cloudns.cl. 2 NS ns103.cloudns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0