mx-b1-01.pyur.net has no CNAME records.
Question and response
Question
dig mx-b1-01.pyur.net. NS
Answer
The response has no answer records.
Authority
pyur.net. 3077 SOA nspaut-b1-01.mip-platform.net. hostmaster.mip-platform.net. 1758699817 3600 300 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0