Apex domains cannot have CNAME records.
Question and response
Question
dig interbild.net. NS
Answer
interbild.net. 2 NS byte.dns-parking.com.
interbild.net. 2 NS pixel.dns-parking.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0