Apex domains cannot have CNAME records.
Question and response
Question
dig cloudns.nz. NS
Answer
cloudns.nz. 5 NS ns44.cloudns.net.
cloudns.nz. 5 NS ns42.cloudns.net.
cloudns.nz. 5 NS ns41.cloudns.net.
cloudns.nz. 5 NS ns43.cloudns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0