mail64.dim165.sgpsv.com has no NS records.
NS records for this zone are defined at sgpsv.com.
NS records for this zone are defined at sgpsv.com.
Question and response
Question
dig mail64.dim165.sgpsv.com. NS
Answer
The response has no answer records.
Authority
sgpsv.com. 300 SOA ns-cloud-c1.googledomains.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0