Apex domains cannot have CNAME records.
Question and response
Question
dig icip.de. NS
Answer
icip.de. 5 NS nsc8.schlundtech.de.
icip.de. 5 NS ns10.icip.de.
Authority
The response has no authority records.
Additional
ns10.icip.de. 5 A 62.141.38.142
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0