Apex domains cannot have CNAME records.
Question and response
Question
dig austriacloud.at. NS
Answer
austriacloud.at. 5 NS dns4.a1.net.
austriacloud.at. 5 NS dns5.a1.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0