Apex domains cannot have CNAME records.
Question and response
Question
dig opusnet.com. NS
Answer
opusnet.com. 5 NS ns1.opusinteractive.io.
opusnet.com. 5 NS ns3.opusinteractive.io.
opusnet.com. 5 NS ns2.opusinteractive.io.
Authority
The response has no authority records.
Additional
ns1.opusinteractive.io. 5 A 216.151.4.2
ns2.opusinteractive.io. 5 A 205.235.95.100
ns3.opusinteractive.io. 5 A 199.101.208.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0