Apex domains cannot have CNAME records.
Question and response
Question
dig static.tpgi.com.au. NS
Answer
static.tpgi.com.au. 5 NS ns1.tpgi.com.au.
static.tpgi.com.au. 5 NS ns2.tpgi.com.au.
Authority
The response has no authority records.
Additional
ns1.tpgi.com.au. 4 A 203.12.160.40
ns2.tpgi.com.au. 4 A 203.26.24.40
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0