s1._domainkey.fbnet.com.br has no NS records.
NS records for this zone are defined at fbnet.com.br.
NS records for this zone are defined at fbnet.com.br.
Question and response
Question
dig s1.domainkey.u22591655.wl156.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl156.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399564753 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0