Apex domains cannot have CNAME records.
Question and response
Question
dig voxdsl.co.za. NS
Answer
voxdsl.co.za. 4 NS ns2.voxdns.co.za.
voxdsl.co.za. 4 NS ns1.voxdns.co.za.
Authority
The response has no authority records.
Additional
ns1.voxdns.co.za. 2 A 41.193.38.221
ns2.voxdns.co.za. 2 A 41.193.38.222
ns1.voxdns.co.za. 2 AAAA 2c0f:fd58:0:0:0:0:0:10
ns2.voxdns.co.za. 2 AAAA 2c0f:fd58:0:0:0:0:0:11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0