ms6.sendsrv.com has no NS records.
NS records for this zone are defined at sendsrv.com.
NS records for this zone are defined at sendsrv.com.
Question and response
Question
dig ms6.sendsrv.com. NS
Answer
The response has no answer records.
Authority
sendsrv.com. 3600 SOA ns3.nitric.co.za. hostmaster.nitric.co.za. 2018011500 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0