spf.mhnet.com.br has no NS records.
NS records for this zone are defined at mhnet.com.br.
NS records for this zone are defined at mhnet.com.br.
Question and response
Question
dig spf.mhnet.com.br. NS
Answer
The response has no answer records.
Authority
mhnet.com.br. 1800 SOA amos.ns.cloudflare.com. dns.cloudflare.com. 2397783533 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0