ctt.ispn.net has no CNAME records.
Question and response
Question
dig ctt.ispn.net. NS
Answer
The response has no answer records.
Authority
ispn.net. 600 SOA ns1.ispn.net. administrator.ispn.net. 2026022500 1800 800 864000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0