Apex domains cannot have CNAME records.
Question and response
Question
dig promotedby.net. NS
Answer
promotedby.net. 1 NS ns-187.awsdns-23.com.
promotedby.net. 1 NS ns-1589.awsdns-06.co.uk.
promotedby.net. 1 NS ns-1366.awsdns-42.org.
promotedby.net. 1 NS ns-577.awsdns-08.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0