Apex domains cannot have CNAME records.
Question and response
Question
dig digitalnbnk.com. NS
Answer
digitalnbnk.com. 4 NS ns-1629.awsdns-11.co.uk.
digitalnbnk.com. 4 NS ns-238.awsdns-29.com.
digitalnbnk.com. 4 NS ns-686.awsdns-21.net.
digitalnbnk.com. 4 NS ns-1260.awsdns-29.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0