Apex domains cannot have CNAME records.
Question and response
Question
dig itsmedia.de. NS
Answer
itsmedia.de. 5 NS ns-497.awsdns-62.com.
itsmedia.de. 5 NS ns-1953.awsdns-52.co.uk.
itsmedia.de. 5 NS ns-1067.awsdns-05.org.
itsmedia.de. 5 NS ns-942.awsdns-53.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0