rt.virtutel.com.au has no CNAME records.
Question and response
Question
dig rt.virtutel.com.au. NS
Answer
The response has no answer records.
Authority
virtutel.com.au. 2084 SOA ns1.virtutel.com.au. noc\@virtutel.com.au. 2025020101 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0