Apex domains cannot have CNAME records.
Question and response
Question
dig ventraip.com.au. NS
Answer
ventraip.com.au. 4 NS ns1.nexigen.digital.
ventraip.com.au. 4 NS ns3.nexigen.digital.
ventraip.com.au. 4 NS ns2.nexigen.digital.
Authority
The response has no authority records.
Additional
ns1.nexigen.digital. 4 A 112.140.176.12
ns2.nexigen.digital. 4 A 112.140.180.136
ns3.nexigen.digital. 4 A 50.116.13.233
ns1.nexigen.digital. 4 AAAA 2400:b800:0:1:0:0:0:13
ns2.nexigen.digital. 4 AAAA 2400:b800:1:1:0:0:0:13
ns3.nexigen.digital. 4 AAAA 2600:3c01:0:0:f03c:91ff:feae:d042
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0