Apex domains cannot have CNAME records.
Question and response
Question
dig nl-tech.ru. NS
Answer
nl-tech.ru. 5 NS serv1.nl-tech.ru.
Authority
The response has no authority records.
Additional
serv1.nl-tech.ru. 5 A 195.161.118.131
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0