Apex domains cannot have CNAME records.
Question and response
Question
dig jobboardmount.com. NS
Answer
jobboardmount.com. 5 NS ns-1140.awsdns-14.org.
jobboardmount.com. 5 NS ns-2044.awsdns-63.co.uk.
jobboardmount.com. 5 NS ns-230.awsdns-28.com.
jobboardmount.com. 5 NS ns-751.awsdns-29.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0