Apex domains cannot have CNAME records.
Question and response
Question
dig z-tp.com. NS
Answer
z-tp.com. 4 NS ns2.kiodns.site.
z-tp.com. 4 NS ns4.kiodns.site.
z-tp.com. 4 NS ns1.kiodns.site.
z-tp.com. 4 NS ns3.kiodns.site.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0