a.st1.ntp.br has no CNAME records.
Question and response
Question
dig a.st1.ntp.br. NS
Answer
The response has no answer records.
Authority
ntp.br. 15015 SOA a.dns.br. hostmaster.registro.br. 2026022801 86400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0