mx.inet.vn has no NS records.
NS records for this zone are defined at inet.vn.
NS records for this zone are defined at inet.vn.
Question and response
Question
dig mx.inet.vn. NS
Answer
The response has no answer records.
Authority
inet.vn. 1800 SOA aiden.ns.cloudflare.com. dns.cloudflare.com. 2396189407 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0