ns3ac.portunity.com has no CNAME records.
Question and response
Question
dig ns3ac.portunity.com. NS
Answer
The response has no answer records.
Authority
portunity.com. 221 SOA nset1.portunity.com. hostmaster.portunity.de. 1710232264 10800 3600 3600000 360
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0