Apex domains cannot have CNAME records.
Question and response
Question
dig tibus.net. NS
Answer
tibus.net. 1 NS dns2.tibus.net.
tibus.net. 1 NS dns1.tibus.net.
Authority
The response has no authority records.
Additional
dns1.tibus.net. 1 A 212.108.94.4
dns2.tibus.net. 1 A 212.108.94.12
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0