b21.brujula.net has no CNAME records.
Question and response
Question
dig b21.brujula.net. NS
Answer
The response has no answer records.
Authority
brujula.net. 1200 SOA dns.brujula.net. dns2.brujula.net. 2025121400 86400 3600 604800 8640
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0