s1._domainkey.tmknet.com.br has no NS records.
NS records for this zone are defined at tmknet.com.br.
NS records for this zone are defined at tmknet.com.br.
Question and response
Question
dig s1.domainkey.u46071247.wl248.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl248.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399875014 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0