mail.tolna.net has no CNAME records.
Question and response
Question
dig mail.tolna.net. NS
Answer
The response has no answer records.
Authority
tolna.net. 10800 SOA ns3.tolna.net. support.tolna.net. 2020052878 86400 7200 3600000 172800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0