wdmn-voip.aureon.com has no CNAME records.
Question and response
Question
dig wdmn-voip.aureon.com. NS
Answer
The response has no answer records.
Authority
aureon.com. 1694 SOA ns3k.aureon.com. hostmaster.netins.net. 2017103610 1800 3000 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0