Apex domains cannot have CNAME records.
Question and response
Question
dig tusker.net.au. NS
Answer
tusker.net.au. 5 NS kolton.ns.cloudflare.com.
tusker.net.au. 5 NS gemma.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0