Apex domains cannot have CNAME records.
Question and response
Question
dig newtel.cz. NS
Answer
newtel.cz. 5 NS ns.axfone.cz.
newtel.cz. 5 NS ns.axfone.sk.
newtel.cz. 5 NS ns.axfone.eu.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0