d.ns.at has no CNAME records.
Question and response
Question
dig d.ns.at. NS
Answer
The response has no answer records.
Authority
at. 10800 SOA dns.nic.at. domain-admin.univie.ac.at. 1772262002 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0