ns2.zsttk.net has no CNAME records.
Question and response
Question
dig ns2.zsttk.net. NS
Answer
The response has no answer records.
Authority
zsttk.net. 10800 SOA ns.zsttk.ru. hostmaster.zsttk.ru. 2021052709 43200 3600 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0