mx01.mail.alibaba.com has no CNAME records.
Question and response
Question
dig mx01.mail.alibaba.com. NS
Answer
The response has no answer records.
Authority
alibaba.com. 255 SOA ns1.alibabadns.com. hostmaster.alibabadns.com. 2018051019 3600 1200 86400 360
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0