ns-c.naamserver.net has no CNAME records.
Question and response
Question
dig ns-c.naamserver.net. NS
Answer
The response has no answer records.
Authority
naamserver.net. 10765 SOA ns.naamserver.net. hostmaster.naamserver.net. 2021102103 14400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0