Apex domains cannot have CNAME records.
Question and response
Question
dig esker.com.au. NS
Answer
esker.com.au. 5 NS ns-118-c.gandi.net.
esker.com.au. 5 NS ns-109-a.gandi.net.
esker.com.au. 5 NS ns-119-b.gandi.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0