Apex domains cannot have CNAME records.
Question and response
Question
dig spam03.arvid.ee. NS
Answer
spam03.arvid.ee. 5 NS ns.isphost.net.
spam03.arvid.ee. 5 NS ns2.isphost.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0