Apex domains cannot have CNAME records.
Question and response
Question
dig vox.co.za. NS
Answer
vox.co.za. 2 NS ns1.voxdns.co.za.
vox.co.za. 2 NS ns2.voxdns.co.za.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0