Apex domains cannot have CNAME records.
Question and response
Question
dig X5-TECH.ru. NS
Answer
x5-tech.ru. 1 NS ns4-l2.nic.ru.
x5-tech.ru. 1 NS ns2.x5.ru.
x5-tech.ru. 1 NS ns1.x5.ru.
x5-tech.ru. 1 NS ns8-l2.nic.ru.
Authority
The response has no authority records.
Additional
ns1.x5.ru. 2 A 193.232.108.106
ns2.x5.ru. 2 A 193.232.108.61
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0