ns2.den.RU has no CNAME records.
Question and response
Question
dig ns2.den.RU. NS
Answer
The response has no answer records.
Authority
den.ru. 8187 SOA ve.nu. hostmaster.den.ru. 2025080201 10800 3600 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0