Apex domains cannot have CNAME records.
Question and response
Question
dig acw.at. NS
Answer
acw.at. 5 NS ns.acw.at.
acw.at. 5 NS ns2.acw.at.
Authority
The response has no authority records.
Additional
ns.acw.at. 5 A 217.116.176.2
ns2.acw.at. 5 A 217.116.186.130
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0