mx2.korbank.com has no CNAME records.
Question and response
Question
dig mx2.korbank.com. NS
Answer
The response has no answer records.
Authority
korbank.com. 10800 SOA dns.korbank.com. hostmaster.korbank.pl. 2024080460 86400 300 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0