Apex domains cannot have CNAME records.
Question and response
Question
dig ontecnologia.com. NS
Answer
ontecnologia.com. 3 NS ns-256.awsdns-32.com.
ontecnologia.com. 3 NS ns-1632.awsdns-12.co.uk.
ontecnologia.com. 3 NS ns-1586.awsdns-06.co.uk.
ontecnologia.com. 3 NS ns-1429.awsdns-50.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0