mails.online.com.kh has no NS records.
NS records for this zone are defined at online.com.kh.
NS records for this zone are defined at online.com.kh.
Question and response
Question
dig mails.online.com.kh. NS
Answer
The response has no answer records.
Authority
online.com.kh. 3600 SOA dns1.online.com.kh. hostmaster.online.com.kh. 2026022502 10800 3600 43200 43200
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0