mx-mg.ipower.com has no CNAME records.
Question and response
Question
dig mx-mg.ipower.com. NS
Answer
The response has no answer records.
Authority
ipower.com. 2857 SOA ns1.ipowerweb.net. hostmaster.ipowerweb.net. 2007042301 80000 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0