mx2.lunixsys.com has no CNAME records.
Question and response
Question
dig mx2.lunixsys.com. NS
Answer
The response has no answer records.
Authority
lunixsys.com. 5964 SOA ns.lunixsys.com. hostmaster\@lunixsys.com. 2023082800 28800 14400 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0