Apex domains cannot have CNAME records.
Question and response
Question
dig holzweg.tv. NS
Answer
holzweg.tv. 5 NS ns3.second-ns.de.
holzweg.tv. 5 NS ns1.your-server.de.
holzweg.tv. 5 NS ns.second-ns.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0