mta6.serverlet.com has no NS records.
NS records for this zone are defined at serverlet.com.
NS records for this zone are defined at serverlet.com.
Question and response
Question
dig mta6.serverlet.com. NS
Answer
The response has no answer records.
Authority
serverlet.com. 3600 SOA ns1.serverlet.com. info.serverlet.com. 2026022393 10000 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0