sip6.ornethd.net has no CNAME records.
Question and response
Question
dig sip6.ornethd.net. NS
Answer
The response has no answer records.
Authority
ornethd.net. 6877 SOA ns1.ornethd.net. admin.ornethd.net. 1433947188 10800 3600 604800 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0