mail.sdmarc.net has no NS records.
NS records for this zone are defined at sdmarc.net.
NS records for this zone are defined at sdmarc.net.
Question and response
Question
dig mail.sdmarc.net. NS
Answer
The response has no answer records.
Authority
sdmarc.net. 1800 SOA ns1.sendmarc.net. dns.cloudflare.com. 2398059740 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0