mailcore.nwi.net has no CNAME records.
Question and response
Question
dig mailcore.nwi.net. NS
Answer
The response has no answer records.
Authority
nwi.net. 3510 SOA ns1.nwinternet.com. hostmaster.nwinternet.com. 2026022001 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0