Apex domains cannot have CNAME records.
Question and response
Question
dig govix.at. NS
Answer
govix.at. 5 NS ns5.univie.ac.at.
govix.at. 5 NS ns11.govix.at.
Authority
The response has no authority records.
Additional
ns5.univie.ac.at. 2 A 193.171.255.77
ns11.govix.at. 2 A 192.76.243.11
ns5.univie.ac.at. 2 AAAA 2001:628:453:4305:0:0:0:53
ns11.govix.at. 2 AAAA 2001:67c:133c:0:0:0:0:11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0