dns1.vnnic.vn has no NS records.
NS records for this zone are defined at vnnic.vn.
NS records for this zone are defined at vnnic.vn.
Question and response
Question
dig dns1.vnnic.vn. NS
Answer
The response has no answer records.
Authority
vnnic.vn. 5400 SOA dns1.vnnic.vn. postmaster.vnnic.vn. 2023035900 1800 900 604800 5400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0