Apex domains cannot have CNAME records.
Question and response
Question
dig faxonline.at. NS
Answer
faxonline.at. 5 NS ns-400.awsdns-50.com.
faxonline.at. 5 NS ns-1039.awsdns-01.org.
faxonline.at. 5 NS ns-921.awsdns-51.net.
faxonline.at. 5 NS ns-1807.awsdns-33.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0