Apex domains cannot have CNAME records.
Question and response
Question
dig dl.sm.ua. NS
Answer
dl.sm.ua. 5 NS ns13.cloudns.net.
dl.sm.ua. 5 NS ns12.cloudns.net.
dl.sm.ua. 5 NS ns11.cloudns.net.
dl.sm.ua. 5 NS ns14.cloudns.net.
dl.sm.ua. 5 NS pns13.cloudns.net.
dl.sm.ua. 5 NS pns12.cloudns.net.
dl.sm.ua. 5 NS pns11.cloudns.net.
dl.sm.ua. 5 NS pns14.cloudns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0