Apex domains cannot have CNAME records.
Question and response
Question
dig linkbynet.com. NS
Answer
linkbynet.com. 4 NS ns2.linkbynet.com.
linkbynet.com. 4 NS ns1.linkbynet.com.
linkbynet.com. 4 NS ns3.linkbynet.com.
Authority
The response has no authority records.
Additional
ns1.linkbynet.com. 4 A 217.19.48.80
ns2.linkbynet.com. 4 A 217.19.60.80
ns3.linkbynet.com. 4 A 162.208.12.238
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0