Apex domains cannot have CNAME records.
Question and response
Question
dig vadesecure.com. NS
Answer
vadesecure.com. 5 NS ns-159.awsdns-19.com.
vadesecure.com. 5 NS ns-894.awsdns-47.net.
vadesecure.com. 5 NS ns-1471.awsdns-55.org.
vadesecure.com. 5 NS ns-1971.awsdns-54.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0