ns4.nsgrid.net has no CNAME records.
Question and response
Question
dig ns4.nsgrid.net. NS
Answer
The response has no answer records.
Authority
nsgrid.net. 1800 SOA ns1.nsgrid.net. dns.nsgrid.net. 2022184093 3600 600 43200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0