Apex domains cannot have CNAME records.
Question and response
Question
dig mopo.de. NS
Answer
mopo.de. 4 NS ns.udag.net.
mopo.de. 4 NS ns.udag.de.
mopo.de. 4 NS ns.udag.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0