mx4.casjayvpn.cc has no CNAME records.
Question and response
Question
dig mx4.casjayvpn.cc. NS
Answer
The response has no answer records.
Authority
casjayvpn.cc. 4805 SOA dns.casjayvpn.cc. dns-admin.casjayvpn.cc. 2026010306 10800 3600 1209600 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0