mailsg.sg.dc.integral.net has no NS records.
NS records for this zone are defined at integral.net.
NS records for this zone are defined at integral.net.
Question and response
Question
dig mailsg.sg.dc.integral.net. NS
Answer
The response has no answer records.
Authority
integral.net. 900 SOA ns-542.awsdns-03.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0