default-rdns.vocus.co.nz has no CNAME records.
Question and response
Question
dig default-rdns.vocus.co.nz. NS
Answer
The response has no answer records.
Authority
vocus.co.nz. 879 SOA ns-506.awsdns-63.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0