Apex domains cannot have CNAME records.
Question and response
Question
dig ns.ro. NS
Answer
ns.ro. 5 NS a.ns.ro.
ns.ro. 5 NS b.ns.ro.
Authority
The response has no authority records.
Additional
a.ns.ro. 5 A 188.214.105.203
b.ns.ro. 5 A 188.214.105.203
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0