Apex domains cannot have CNAME records.
Question and response
Question
dig downtobusinessenglish.org. NS
Answer
downtobusinessenglish.org. 5 NS ns-1191.awsdns-20.org.
downtobusinessenglish.org. 5 NS ns-1711.awsdns-21.co.uk.
downtobusinessenglish.org. 5 NS ns-321.awsdns-40.com.
downtobusinessenglish.org. 5 NS ns-571.awsdns-07.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0