mx2.dotvndns.vn has no NS records.
NS records for this zone are defined at dotvndns.vn.
NS records for this zone are defined at dotvndns.vn.
Question and response
Question
dig mx2.dotvndns.vn. NS
Answer
The response has no answer records.
Authority
dotvndns.vn. 3600 SOA ns1.dotvndns.vn. hostmaster.dotvndns.vn. 2025120203 14400 3600 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0