Apex domains cannot have CNAME records.
Question and response
Question
dig oktawave.com. NS
Answer
oktawave.com. 5 NS ns1.oktawave.com.
oktawave.com. 5 NS ns2.oktawave.com.
oktawave.com. 5 NS ns3.oktawave.com.
Authority
The response has no authority records.
Additional
ns1.oktawave.com. 5 A 195.149.198.53
ns2.oktawave.com. 5 A 193.200.66.198
ns3.oktawave.com. 5 A 91.226.194.67
ns1.oktawave.com. 5 AAAA 2a03:d60:0:1:2:149:198:53
ns2.oktawave.com. 5 AAAA 2001:1a68:7:10:193:200:66:198
ns3.oktawave.com. 5 AAAA 2a03:d60:2:250:91:226:194:67
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0