Apex domains cannot have CNAME records.
Question and response
Question
dig weg.de. NS
Answer
weg.de. 1 NS ns-772.awsdns-32.net.
weg.de. 1 NS ns-118.awsdns-14.com.
weg.de. 1 NS ns-2035.awsdns-62.co.uk.
weg.de. 1 NS ns-1222.awsdns-24.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0