mx03.simplyhosting.cloud has no CNAME records.
Question and response
Question
dig mx03.simplyhosting.cloud. NS
Answer
The response has no answer records.
Authority
simplyhosting.cloud. 319 SOA ns01.simplyhosting.cloud. hostmaster.simplyhosting.cloud. 110 3600 600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0