Apex domains cannot have CNAME records.
Question and response
Question
dig aridns.net.au. NS
Answer
aridns.net.au. 5 NS ari.gamma.aridns.net.au.
aridns.net.au. 5 NS ari.delta.aridns.net.au.
aridns.net.au. 5 NS ari.beta.aridns.net.au.
aridns.net.au. 5 NS ari.alpha.aridns.net.au.
Authority
The response has no authority records.
Additional
ari.beta.aridns.net.au. 5 A 37.209.194.2
ari.alpha.aridns.net.au. 5 A 37.209.192.2
ari.delta.aridns.net.au. 5 A 37.209.198.2
ari.gamma.aridns.net.au. 5 A 37.209.196.2
ari.beta.aridns.net.au. 5 AAAA 2001:dcd:2:0:0:0:0:2
ari.alpha.aridns.net.au. 5 AAAA 2001:dcd:1:0:0:0:0:2
ari.delta.aridns.net.au. 5 AAAA 2001:dcd:4:0:0:0:0:2
ari.gamma.aridns.net.au. 5 AAAA 2001:dcd:3:0:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0