Apex domains cannot have CNAME records.
Question and response
Question
dig sendmail.co.nz. NS
Answer
sendmail.co.nz. 4 NS ns1.nameserverz.com.
sendmail.co.nz. 4 NS ns2.nameserverz.com.
Authority
The response has no authority records.
Additional
ns1.nameserverz.com. 4 A 103.248.176.140
ns2.nameserverz.com. 4 A 202.37.129.10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0