mail17.centercode.com has no NS records.
NS records for this zone are defined at centercode.com.
NS records for this zone are defined at centercode.com.
Question and response
Question
dig mail17.centercode.com. NS
Answer
The response has no answer records.
Authority
centercode.com. 900 SOA ns-725.awsdns-26.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0