Apex domains cannot have CNAME records.
Question and response
Question
dig themailspec.com. NS
Answer
themailspec.com. 4 NS pns3.cloud.sg.
themailspec.com. 4 NS pns1.cloud.sg.
themailspec.com. 4 NS pns2.cloud.sg.
themailspec.com. 4 NS pns4.cloud.sg.
Authority
The response has no authority records.
Additional
pns1.cloud.sg. 4 A 185.136.96.96
pns2.cloud.sg. 4 A 185.136.97.96
pns3.cloud.sg. 4 A 185.136.98.96
pns4.cloud.sg. 4 A 185.136.99.96
pns1.cloud.sg. 4 AAAA 2a06:fb00:1:0:0:0:1:96
pns2.cloud.sg. 4 AAAA 2a06:fb00:1:0:0:0:2:96
pns3.cloud.sg. 4 AAAA 2a06:fb00:1:0:0:0:3:96
pns4.cloud.sg. 4 AAAA 2a06:fb00:1:0:0:0:4:96
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0