mail.hostia.net has no CNAME records.
Question and response
Question
dig mail.hostia.net. NS
Answer
The response has no answer records.
Authority
hostia.net. 1507 SOA ns1.hostia.net. server.hostia.net. 2022052518 14400 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0