f.dns.br has no CNAME records.
Question and response
Question
dig f.dns.br. NS
Answer
The response has no answer records.
Authority
dns.br. 61589 SOA a.dns.br. hostmaster.registro.br. 2026022102 86400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0