Apex domains cannot have CNAME records.
Question and response
Question
dig exetel.com.au. NS
Answer
exetel.com.au. 5 NS ns-195.awsdns-24.com.
exetel.com.au. 5 NS ns-1107.awsdns-10.org.
exetel.com.au. 5 NS ns-712.awsdns-25.net.
exetel.com.au. 5 NS ns-1969.awsdns-54.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0