Apex domains cannot have CNAME records.
Question and response
Question
dig dnsbox.net. NS
Answer
dnsbox.net. 5 NS ns.dnsbox.net.
Authority
The response has no authority records.
Additional
ns.dnsbox.net. 5 A 208.53.48.154
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0