Apex domains cannot have CNAME records.
Question and response
Question
dig dexterousnetwork.com. NS
Answer
dexterousnetwork.com. 5 NS ns1.dexterousnetwork.com.
dexterousnetwork.com. 5 NS ns2.dexterousnetwork.com.
Authority
The response has no authority records.
Additional
ns1.dexterousnetwork.com. 5 A 104.206.1.174
ns2.dexterousnetwork.com. 5 A 173.232.67.244
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0