Apex domains cannot have CNAME records.
Question and response
Question
dig mxserver.ro. NS
Answer
mxserver.ro. 5 NS tani.ns.cloudflare.com.
mxserver.ro. 5 NS norman.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0