mail.intrabit.net has no CNAME records.
Question and response
Question
dig mail.intrabit.net. NS
Answer
The response has no answer records.
Authority
intrabit.net. 7480 SOA ns01.intrabit.net. domains.intrabit.net. 2026021500 43200 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0