rt.broadwick.com has no CNAME records.
Question and response
Question
dig rt.broadwick.com. NS
Answer
The response has no answer records.
Authority
broadwick.com. 444 SOA carol.ns.cloudflare.com. dns.cloudflare.com. 2396287630 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0