Apex domains cannot have CNAME records.
Question and response
Question
dig ainet.at. NS
Answer
ainet.at. 5 NS dns2.ainet.at.
ainet.at. 5 NS dns1.ainet.at.
Authority
The response has no authority records.
Additional
dns1.ainet.at. 5 A 87.243.128.30
dns2.ainet.at. 5 A 87.243.129.30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0