Apex domains cannot have CNAME records.
Question and response
Question
dig col.agava.net. NS
Answer
col.agava.net. 5 NS ns1.reg.ru.
col.agava.net. 5 NS ns2.reg.ru.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0