Apex domains cannot have CNAME records.
Question and response
Question
dig choruscallaustralia.com.au. NS
Answer
choruscallaustralia.com.au. 5 NS ns2.choruscallaustralia.com.au.
choruscallaustralia.com.au. 5 NS ns1.choruscallaustralia.com.au.
Authority
The response has no authority records.
Additional
ns1.choruscallaustralia.com.au. 5 A 110.173.132.58
ns2.choruscallaustralia.com.au. 5 A 110.173.132.58
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0