spf.servidor.srv.br has no NS records.
NS records for this zone are defined at servidor.srv.br.
NS records for this zone are defined at servidor.srv.br.
Question and response
Question
dig spf.servidor.srv.br. NS
Answer
The response has no answer records.
Authority
servidor.srv.br. 1800 SOA fay.ns.cloudflare.com. dns.cloudflare.com. 2397102020 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0