Apex domains cannot have CNAME records.
Question and response
Question
dig onenet.co.nz. NS
Answer
onenet.co.nz. 5 NS piper.ns.cloudflare.com.
onenet.co.nz. 5 NS ray.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0