Apex domains cannot have CNAME records.
Question and response
Question
dig bkbookids.com. NS
Answer
bkbookids.com. 5 NS ns-853.awsdns-42.net.
bkbookids.com. 5 NS ns-1728.awsdns-24.co.uk.
bkbookids.com. 5 NS ns-1758.awsdns-27.co.uk.
bkbookids.com. 5 NS ns-723.awsdns-26.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0