Apex domains cannot have CNAME records.
Question and response
Question
dig siberianet.ru. NS
Answer
SIBERIANET.RU. 2 NS tia.ns.cloudflare.com.
SIBERIANET.RU. 2 NS julio.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
tia.ns.cloudflare.com. 3 A 108.162.192.229
tia.ns.cloudflare.com. 3 A 172.64.32.229
tia.ns.cloudflare.com. 3 A 173.245.58.229
julio.ns.cloudflare.com. 3 A 108.162.195.209
julio.ns.cloudflare.com. 3 A 162.159.44.209
julio.ns.cloudflare.com. 3 A 172.64.35.209
tia.ns.cloudflare.com. 3 AAAA 2606:4700:50:0:0:0:adf5:3ae5
tia.ns.cloudflare.com. 3 AAAA 2803:f800:50:0:0:0:6ca2:c0e5
tia.ns.cloudflare.com. 3 AAAA 2a06:98c1:50:0:0:0:ac40:20e5
julio.ns.cloudflare.com. 3 AAAA 2606:4700:58:0:0:0:a29f:2cd1
julio.ns.cloudflare.com. 3 AAAA 2803:f800:50:0:0:0:6ca2:c3d1
julio.ns.cloudflare.com. 3 AAAA 2a06:98c1:50:0:0:0:ac40:23d1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0