Apex domains cannot have CNAME records.
Question and response
Question
dig gyrocopter.sinc.cl. NS
Answer
gyrocopter.sinc.cl. 5 NS ns2.gyrocopter.sinc.cl.
gyrocopter.sinc.cl. 5 NS ns1.gyrocopter.sinc.cl.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0