Apex domains cannot have CNAME records.
Question and response
Question
dig yourdomain.co.za. NS
Answer
yourdomain.co.za. 5 NS dns1.co.za.
yourdomain.co.za. 5 NS dns2.co.za.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0