Apex domains cannot have CNAME records.
Question and response
Question
dig promaserv.net. NS
Answer
promaserv.net. 5 NS ns-834.awsdns-40.net.
promaserv.net. 5 NS ns-1732.awsdns-24.co.uk.
promaserv.net. 5 NS ns-1943.awsdns-50.co.uk.
promaserv.net. 5 NS ns-733.awsdns-27.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0