mailsvr.supportsystem.com has no NS records.
NS records for this zone are defined at supportsystem.com.
NS records for this zone are defined at supportsystem.com.
Question and response
Question
dig mailsvr.supportsystem.com. NS
Answer
The response has no answer records.
Authority
supportsystem.com. 900 SOA ns-951.awsdns-54.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0