Apex domains cannot have CNAME records.
Question and response
Question
dig inx.net.za. NS
Answer
inx.net.za. 4 NS ns1.inx.net.za.
inx.net.za. 4 NS ns2.inx.net.za.
inx.net.za. 4 NS ns3.inx.net.za.
Authority
The response has no authority records.
Additional
ns1.inx.net.za. 4 A 196.10.52.53
ns2.inx.net.za. 4 A 196.10.54.53
ns3.inx.net.za. 4 A 196.10.55.53
ns1.inx.net.za. 4 AAAA 2001:43f8:1f3:100:0:0:0:53
ns2.inx.net.za. 4 AAAA 2001:43f8:1f4:100:0:0:0:53
ns3.inx.net.za. 4 AAAA 2001:43f8:1f5:100:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0