Apex domains cannot have CNAME records.
Question and response
Question
dig crucialx.net. NS
Answer
crucialx.net. 4 NS nssyd01.crucial.com.au.
crucialx.net. 4 NS nsdal01.crucial.com.au.
crucialx.net. 4 NS nssyd02.crucial.com.au.
Authority
The response has no authority records.
Additional
nsdal01.crucial.com.au. 4 A 128.199.123.135
nssyd01.crucial.com.au. 4 A 111.118.163.5
nssyd02.crucial.com.au. 4 A 182.160.129.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0