a.ns.UDMVT.RU has no CNAME records.
Question and response
Question
dig a.ns.UDMVT.RU. NS
Answer
The response has no answer records.
Authority
udmvt.ru. 1174 SOA a.ns.udmvt.ru. hostmaster.udmvt.ru. 2021101449 86400 7200 4838400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0