Apex domains cannot have CNAME records.
Question and response
Question
dig bitrixsoft.com. NS
Answer
bitrixsoft.com. 1 NS ns-993.awsdns-60.net.
bitrixsoft.com. 1 NS ns-242.awsdns-30.com.
bitrixsoft.com. 1 NS ns-1642.awsdns-13.co.uk.
bitrixsoft.com. 1 NS ns-1385.awsdns-45.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0