Apex domains cannot have CNAME records.
Question and response
Question
dig BC9C1F72.catv.pool.telekom.hu. NS
Answer
BC9C1F72.catv.pool.telekom.hu. 5 NS pns1.telekom.hu.
BC9C1F72.catv.pool.telekom.hu. 5 NS pns0.telekom.hu.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0