spf.host.srv.br has no NS records.
NS records for this zone are defined at host.srv.br.
NS records for this zone are defined at host.srv.br.
Question and response
Question
dig spf.host.srv.br. NS
Answer
The response has no answer records.
Authority
host.srv.br. 1800 SOA andy.ns.cloudflare.com. dns.cloudflare.com. 2397546207 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0