Apex domains cannot have CNAME records.
Question and response
Question
dig docs.uahosting.com.ua. NS
Answer
docs.uahosting.com.ua. 5 NS ns2.uahosting.com.ua.
docs.uahosting.com.ua. 5 NS ns1.uahosting.com.ua.
Authority
The response has no authority records.
Additional
ns1.uahosting.com.ua. 5 A 57.128.218.24
ns2.uahosting.com.ua. 5 A 116.202.25.228
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0