Apex domains cannot have CNAME records.
Question and response
Question
dig securebooking.org. NS
Answer
securebooking.org. 5 NS ns2.nitric.co.za.
securebooking.org. 5 NS ns1.nitric.co.za.
securebooking.org. 5 NS ns3.nitric.co.za.
Authority
The response has no authority records.
Additional
ns1.nitric.co.za. 2 A 45.33.0.158
ns2.nitric.co.za. 2 A 173.255.244.177
ns3.nitric.co.za. 2 A 173.255.244.234
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0