Apex domains cannot have CNAME records.
Question and response
Question
dig dnsvisa.com. NS
Answer
dnsvisa.com. 5 NS ns1.dnsvisa.com.
dnsvisa.com. 5 NS ns2.dnsvisa.com.
dnsvisa.com. 5 NS ns3.dnsvisa.com.
Authority
The response has no authority records.
Additional
ns1.dnsvisa.com. 5 A 162.159.9.153
ns2.dnsvisa.com. 5 A 162.159.8.235
ns3.dnsvisa.com. 5 A 162.159.11.57
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0