mail3.netcon.at has no CNAME records.
Question and response
Question
dig mail3.netcon.at. NS
Answer
The response has no answer records.
Authority
netcon.at. 9562 SOA isp1.netcon.at. postmaster.netcon.at. 2026020602 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0