Apex domains cannot have CNAME records.
Question and response
Question
dig server.aderlo.cloud. NS
Answer
server.aderlo.cloud. 5 NS ns2.aderlo.cloud.
server.aderlo.cloud. 5 NS ns1.aderlo.cloud.
Authority
The response has no authority records.
Additional
ns1.aderlo.cloud. 5 A 185.200.45.148
ns2.aderlo.cloud. 5 A 185.200.45.148
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0