m16b.cvtsv.com has no NS records.
NS records for this zone are defined at cvtsv.com.
NS records for this zone are defined at cvtsv.com.
Question and response
Question
dig m16b.cvtsv.com. NS
Answer
The response has no answer records.
Authority
cvtsv.com. 900 SOA ns-654.awsdns-17.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0