mx01.nic.net.sa has no CNAME records.
Question and response
Question
dig mx01.nic.net.sa. NS
Answer
The response has no answer records.
Authority
nic.net.sa. 2921 SOA ns1.nic.sa. hostmaster.nic.sa. 2026022504 10800 3600 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0