Apex domains cannot have CNAME records.
Question and response
Question
dig 3g.vodacom.co.za. NS
Answer
3g.vodacom.co.za. 3 NS dnsinfo1-mtp-auth.3g.vodacom.co.za.
3g.vodacom.co.za. 3 NS dnsinfo1-cte-auth.3g.vodacom.co.za.
Authority
The response has no authority records.
Additional
dnsinfo1-cte-auth.3g.vodacom.co.za. 3 A 41.1.47.251
dnsinfo1-mtp-auth.3g.vodacom.co.za. 3 A 41.1.239.251
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0