Apex domains cannot have CNAME records.
Question and response
Question
dig lnk.telstra.net. NS
Answer
lnk.telstra.net. 5 NS dns0.telstra.net.
lnk.telstra.net. 5 NS dns1.telstra.net.
Authority
The response has no authority records.
Additional
dns0.telstra.net. 4 A 203.50.248.13
dns1.telstra.net. 4 A 203.50.248.14
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0