Apex domains cannot have CNAME records.
Question and response
Question
dig hfmlive.de.com. NS
Answer
hfmlive.de.com. 1 NS rayne.ns.cloudflare.com.
hfmlive.de.com. 1 NS ruben.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0