Apex domains cannot have CNAME records.
Question and response
Question
dig fastdns.hosting. NS
Answer
fastdns.hosting. 5 NS ns2.fastdns.hosting.
fastdns.hosting. 5 NS ns1.fastdns.hosting.
fastdns.hosting. 5 NS ns3.fastdns.hosting.
Authority
The response has no authority records.
Additional
ns1.fastdns.hosting. 5 A 91.222.136.45
ns2.fastdns.hosting. 5 A 91.206.200.105
ns3.fastdns.hosting. 5 A 167.235.84.54
ns3.fastdns.hosting. 5 AAAA 2a01:4f8:fff0:142:103:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0