Apex domains cannot have CNAME records.
Question and response
Question
dig docebosaas.com. NS
Answer
docebosaas.com. 5 NS ns-611.awsdns-12.net.
docebosaas.com. 5 NS ns-1031.awsdns-00.org.
docebosaas.com. 5 NS ns-1759.awsdns-27.co.uk.
docebosaas.com. 5 NS ns-196.awsdns-24.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0