Apex domains cannot have CNAME records.
Question and response
Question
dig oxseu-vadesecure.net. NS
Answer
oxseu-vadesecure.net. 5 NS ns-1683.awsdns-18.co.uk.
oxseu-vadesecure.net. 5 NS ns-1432.awsdns-51.org.
oxseu-vadesecure.net. 5 NS ns-186.awsdns-23.com.
oxseu-vadesecure.net. 5 NS ns-620.awsdns-13.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0