Apex domains cannot have CNAME records.
Question and response
Question
dig 5-55.ru. NS
Answer
5-55.ru. 5 NS ns.5-55.ru.
5-55.ru. 5 NS ns1.5-55.ru.
Authority
The response has no authority records.
Additional
ns.5-55.RU. 5 A 91.212.60.162
ns1.5-55.RU. 5 A 195.13.210.226
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0