sbc3.insmartcloud.com has no NS records.
NS records for this zone are defined at insmartcloud.com.
NS records for this zone are defined at insmartcloud.com.
Question and response
Question
dig sbc3.insmartcloud.com. NS
Answer
The response has no answer records.
Authority
insmartcloud.com. 900 SOA ns-888.awsdns-47.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0