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