Apex domains cannot have CNAME records.
Question and response
Question
dig 1-grid-mx01.co.za. NS
Answer
1-grid-mx01.co.za. 5 NS ns2.hostserv.co.za.
1-grid-mx01.co.za. 5 NS ns1.hostserv.co.za.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0