Apex domains cannot have CNAME records.
Question and response
Question
dig strongns.net. NS
Answer
strongns.net. 5 NS freedns2.registrar-servers.com.
strongns.net. 5 NS freedns3.registrar-servers.com.
strongns.net. 5 NS freedns1.registrar-servers.com.
strongns.net. 5 NS freedns5.registrar-servers.com.
strongns.net. 5 NS freedns4.registrar-servers.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0