mona2.singtel.com has no NS records.
NS records for this zone are defined at singtel.com.
NS records for this zone are defined at singtel.com.
Question and response
Question
dig mona2.singtel.com. NS
Answer
The response has no answer records.
Authority
singtel.com. 600 SOA dnspri.singnet.com.sg. hostmaster.singnet.com.sg. 2025100969 3600 1800 604800 28800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0