Apex domains cannot have CNAME records.
Question and response
Question
dig qsl.net.au. NS
Answer
qsl.net.au. 5 NS ns1.melbourneit.net.
qsl.net.au. 5 NS ns3.melbourneit.net.
qsl.net.au. 5 NS ns2.melbourneit.net.
qsl.net.au. 5 NS ns4.melbourneit.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0