mx.qd-tgl.com has no CNAME records.
Question and response
Question
dig mx.qd-tgl.com. NS
Answer
The response has no answer records.
Authority
qd-tgl.com. 3127 SOA dns.qd-tgl.com. hostmaster.qd-tgl.com. 1622169515 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0