Apex domains cannot have CNAME records.
Question and response
Question
dig reasonable53.com. NS
Answer
reasonable53.com. 2 NS ns1.onlydomains.com.
reasonable53.com. 2 NS ns3.onlydomains.com.
reasonable53.com. 2 NS ns2.onlydomains.com.
Authority
The response has no authority records.
Additional
ns1.onlydomains.com. 2 A 75.2.6.34
ns2.onlydomains.com. 2 A 75.2.85.37
ns3.onlydomains.com. 2 A 130.180.201.164
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0