Apex domains cannot have CNAME records.
Question and response
Question
dig SAMTEL.RU. NS
Answer
SAMTEL.RU. 5 NS ns2.SAMTEL.RU.
SAMTEL.RU. 5 NS ns1.SAMTEL.RU.
Authority
The response has no authority records.
Additional
ns1.SAMTEL.RU. 5 A 62.213.0.12
ns2.samtel.RU. 5 A 62.213.2.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0