mail.provus.com.tr has no CNAME records.
Question and response
Question
dig mail.provus.com.tr. NS
Answer
The response has no answer records.
Authority
provus.com.tr. 1499 SOA dnx1.vodafone.net.tr. dnsadmin.provus.com.tr. 2019070109 86400 7200 3628800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0