Apex domains cannot have CNAME records.
Question and response
Question
dig net.unsw.edu.au. NS
Answer
net.unsw.edu.au. 5 NS ns3-ext.unsw.edu.au.
net.unsw.edu.au. 5 NS ns1-ext.unsw.edu.au.
net.unsw.edu.au. 5 NS ns2-ext.unsw.edu.au.
Authority
The response has no authority records.
Additional
ns1-ext.unsw.edu.au. 5 A 54.79.80.189
ns2-ext.unsw.edu.au. 5 A 13.236.238.52
ns3-ext.unsw.edu.au. 5 A 54.66.99.146
ns1-ext.unsw.edu.au. 5 AAAA 2001:388:c:35:0:0:0:11
ns2-ext.unsw.edu.au. 5 AAAA 2001:388:c:35:0:0:0:22
ns3-ext.unsw.edu.au. 5 AAAA 2001:388:c:35:0:0:0:33
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0