Apex domains cannot have CNAME records.
Question and response
Question
dig dingobank.com. NS
Answer
dingobank.com. 5 NS ns-1533.awsdns-63.org.
dingobank.com. 5 NS ns-823.awsdns-38.net.
dingobank.com. 5 NS ns-216.awsdns-27.com.
dingobank.com. 5 NS ns-1661.awsdns-15.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0