Apex domains cannot have CNAME records.
Question and response
Question
dig sentris.net. NS
Answer
sentris.net. 5 NS ns2.wahju.com.
sentris.net. 5 NS ns.wahju.com.
sentris.net. 5 NS ns200.wahju.com.
sentris.net. 5 NS ns100.wahju.com.
Authority
The response has no authority records.
Additional
ns100.wahju.com. 5 A 63.223.114.3
ns200.wahju.com. 5 A 107.155.198.79
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0