Apex domains cannot have CNAME records.
Question and response
Question
dig gpdns01.co.za. NS
Answer
gpdns01.co.za. 1 NS main.nameserver4.co.za.
gpdns01.co.za. 1 NS main.nameserver2.co.za.
gpdns01.co.za. 1 NS main.nameserver1.co.za.
gpdns01.co.za. 1 NS main.nameserver3.co.za.
Authority
The response has no authority records.
Additional
main.nameserver1.co.za. 1 A 129.232.149.210
main.nameserver2.co.za. 1 A 46.101.67.77
main.nameserver3.co.za. 1 A 41.203.6.122
main.nameserver4.co.za. 1 A 143.198.240.210
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0