Apex domains cannot have CNAME records.
Question and response
Question
dig za.seacomnet.com. NS
Answer
za.seacomnet.com. 5 NS ns4.seacomnet.com.
za.seacomnet.com. 5 NS ns3.seacomnet.com.
Authority
The response has no authority records.
Additional
ns3.seacomnet.com. 5 A 41.87.126.253
ns4.seacomnet.com. 5 A 41.87.127.253
ns3.seacomnet.com. 5 AAAA 2c0f:feb0:0:0:0:0:0:3
ns4.seacomnet.com. 5 AAAA 2c0f:feb0:0:0:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0