Apex domains cannot have CNAME records.
Question and response
Question
dig filter05.mta.whmpanels.com. NS
Answer
filter05.mta.whmpanels.com. 5 NS ns3.wdp-gazduire.ro.
filter05.mta.whmpanels.com. 5 NS ns4.wdp-gazduire.ro.
filter05.mta.whmpanels.com. 5 NS ns1.wdp-gazduire.ro.
filter05.mta.whmpanels.com. 5 NS ns2.wdp-gazduire.ro.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0