db-1.spb.CDn.GBLNET.RU has no CNAME records.
Question and response
Question
dig db-1.spb.CDn.GBLNET.RU. NS
Answer
The response has no answer records.
Authority
CDn.GBLNET.RU. 9307 SOA localhost. root.localhost. 2026030101 604800 86400 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0