Apex domains cannot have CNAME records.
Question and response
Question
dig mtlan.ru. NS
Answer
mtlan.ru. 3 NS ns1.mtlan.ru.
mtlan.ru. 3 NS ns2.mtlan.ru.
Authority
The response has no authority records.
Additional
ns1.mtlan.ru. 3 A 109.236.208.226
ns2.mtlan.ru. 3 A 134.19.150.42
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0