ruby.c6p.net has no CNAME records.
Question and response
Question
dig ruby.c6p.net. NS
Answer
The response has no answer records.
Authority
c6p.net. 1787 SOA aragorn.ns.cloudflare.com. dns.cloudflare.com. 2397557204 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0