mx6.mobily.com.sa has no CNAME records.
Question and response
Question
dig mx6.mobily.com.sa. NS
Answer
The response has no answer records.
Authority
mobily.com.sa. 415 SOA gm-mlg-01.prod.mobily.lan. hostmaster.mobily.com.sa. 44607 10800 1080 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0