Apex domains cannot have CNAME records.
Question and response
Question
dig smart-weblications.de. NS
Answer
smart-weblications.de. 5 NS ns1.smart-weblications.de.
smart-weblications.de. 5 NS ns2.smart-weblications.de.
Authority
The response has no authority records.
Additional
ns1.smart-weblications.de. 5 A 91.204.168.2
ns2.smart-weblications.de. 5 A 5.230.57.245
ns1.smart-weblications.de. 5 AAAA 2a00:1aa0:c001:c0de:0:0:0:2
ns2.smart-weblications.de. 5 AAAA 2a00:12d8:700e:0:76f0:504a:4b01:8f23
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0