Apex domains cannot have CNAME records.
Question and response
Question
dig lunixsys.com. NS
Answer
lunixsys.com. 1 NS ns1.lunixsys.com.
lunixsys.com. 1 NS ns.ad5ey.net.
lunixsys.com. 1 NS ns2.lunixsys.com.
Authority
The response has no authority records.
Additional
ns.ad5ey.net. 1 A 96.126.100.165
ns1.lunixsys.com. 1 A 173.255.213.159
ns2.lunixsys.com. 1 A 199.58.103.135
ns.ad5ey.net. 1 AAAA 2600:3c01:0:0:f03c:93ff:fe99:222f
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0