Apex domains cannot have CNAME records.
Question and response
Question
dig net.au. NS
Answer
net.au. 5 NS r.au.
net.au. 5 NS q.au.
net.au. 5 NS s.au.
net.au. 5 NS a.au.
net.au. 5 NS t.au.
Authority
The response has no authority records.
Additional
a.au. 21896 A 58.65.254.1
q.au. 172130 A 65.22.196.1
r.au. 172143 A 65.22.197.1
s.au. 172155 A 65.22.198.1
t.au. 172286 A 65.22.199.1
a.au. 21896 AAAA 2407:6e00:254:0:0:0:0:1
q.au. 172130 AAAA 2a01:8840:be:0:0:0:0:1
r.au. 172143 AAAA 2a01:8840:bf:0:0:0:0:1
s.au. 172155 AAAA 2a01:8840:c0:0:0:0:0:1
t.au. 172286 AAAA 2a01:8840:c1:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0