Apex domains cannot have CNAME records.
Question and response
Question
dig sacyrconcesiones.cl. NS
Answer
sacyrconcesiones.cl. 4 NS nsaut.tie.cl.
Authority
The response has no authority records.
Additional
nsaut.tie.cl. 4 A 200.50.96.130
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0