Apex domains cannot have CNAME records.
Question and response
Question
dig WOLFHUGEL.EU. NS
Answer
WOLFHUGEL.EU. 5 NS armoire.WOLFHUGEL.EU.
WOLFHUGEL.EU. 5 NS roubaix.WOLFHUGEL.EU.
WOLFHUGEL.EU. 5 NS gra.WOLFHUGEL.EU.
Authority
The response has no authority records.
Additional
gra.wolfhugel.eu. 5 A 87.98.144.100
armoire.wolfhugel.eu. 5 A 5.135.191.230
gra.wolfhugel.eu. 5 AAAA 2001:41d0:b00:a02:0:0:0:12
armoire.wolfhugel.eu. 5 AAAA 2001:41d0:8:c8e6:0:0:0:1
roubaix.wolfhugel.eu. 5 AAAA 2001:41d0:d00:3202:0:0:0:15
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0