dns.thpttanphu.com has no NS records.
NS records for this zone are defined at thpttanphu.com.
NS records for this zone are defined at thpttanphu.com.
Question and response
Question
dig dns.thpttanphu.com. NS
Answer
The response has no answer records.
Authority
thpttanphu.com. 3600 SOA dns.thpttanphu.com. hostmaster.thpttanphu.com. 1979763074 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0