Apex domains cannot have CNAME records.
Question and response
Question
dig antispam.co.za. NS
Answer
antispam.co.za. 5 NS ns-114.awsdns-14.com.
antispam.co.za. 5 NS ns-1403.awsdns-47.org.
antispam.co.za. 5 NS ns-777.awsdns-33.net.
antispam.co.za. 5 NS ns-1707.awsdns-21.co.uk.
Authority
The response has no authority records.
Additional
ns-114.awsdns-14.com. 3 A 205.251.192.114
ns-777.awsdns-33.net. 3 A 205.251.195.9
ns-1403.awsdns-47.org. 3 A 205.251.197.123
ns-1707.awsdns-21.co.uk. 3 A 205.251.198.171
ns-114.awsdns-14.com. 3 AAAA 2600:9000:5300:7200:0:0:0:1
ns-777.awsdns-33.net. 3 AAAA 2600:9000:5303:900:0:0:0:1
ns-1403.awsdns-47.org. 3 AAAA 2600:9000:5305:7b00:0:0:0:1
ns-1707.awsdns-21.co.uk. 3 AAAA 2600:9000:5306:ab00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0