gw2.mail.techfak.NET has no CNAME records.
Question and response
Question
dig gw2.mail.techfak.NET. NS
Answer
The response has no answer records.
Authority
TechFak.NET. 2320 SOA dns.TechFak.NET. hostmaster.TechFak.NET. 2026022503 86400 7200 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0