Apex domains cannot have CNAME records.
Question and response
Question
dig cielo-sn.com. NS
Answer
cielo-sn.com. 5 NS ns-911.awsdns-49.net.
cielo-sn.com. 5 NS ns-253.awsdns-31.com.
cielo-sn.com. 5 NS ns-1680.awsdns-18.co.uk.
cielo-sn.com. 5 NS ns-1086.awsdns-07.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0