smtp.kana.twdc.com has no NS records.
NS records for this zone are defined at twdc.com.
NS records for this zone are defined at twdc.com.
Question and response
Question
dig smtp.kana.twdc.com. NS
Answer
The response has no answer records.
Authority
twdc.com. 14400 SOA dns1.cscdns.net. hostmaster.cscdns.net. 2025041016 900 300 604800 14400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0