Apex domains cannot have CNAME records.
Question and response
Question
dig 97.238.87.in-addr.arpa. NS
Answer
97.238.87.in-addr.arpa. 4 NS ns2.bsh.ru.
97.238.87.in-addr.arpa. 4 NS ns.bsh.ru.
Authority
The response has no authority records.
Additional
ns.bsh.ru. 5 A 81.95.32.197
ns2.bsh.ru. 5 A 81.95.33.64
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0