mx.iplannetworks.net has no CNAME records.
Question and response
Question
dig mx.iplannetworks.net. NS
Answer
The response has no answer records.
Authority
iplannetworks.net. 4860 SOA ns5.mpower.nl. hostmaster.iplannetworks.net. 2023060901 18000 604800 1209600 604800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0