prometheus.cdn.gblnet.ru has no CNAME records.
Question and response
Question
dig prometheus.cdn.gblnet.ru. NS
Answer
The response has no answer records.
Authority
cdn.gBLNET.ru. 8337 SOA localhost. root.localhost. 2026030101 604800 86400 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0