Apex domains cannot have CNAME records.
Question and response
Question
dig slovakiabr0.com. NS
Answer
slovakiabr0.com. 5 NS ns-330.awsdns-41.com.
slovakiabr0.com. 5 NS ns-1328.awsdns-38.org.
slovakiabr0.com. 5 NS ns-581.awsdns-08.net.
slovakiabr0.com. 5 NS ns-1684.awsdns-18.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0