Apex domains cannot have CNAME records.
Question and response
Question
dig secure-dns.net. NS
Answer
secure-dns.net. 5 NS ns189.secure-dns.net.
secure-dns.net. 5 NS ns188.mschosting.com.
secure-dns.net. 5 NS ns187.mschosting.com.
Authority
The response has no authority records.
Additional
ns187.mschosting.com. 1 A 110.4.46.3
ns188.mschosting.com. 1 A 110.4.41.254
ns189.secure-dns.net. 5 A 72.18.130.34
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0