Apex domains cannot have CNAME records.
Question and response
Question
dig cloud.online.net. NS
Answer
cloud.online.net. 5 NS nsa.online.net.
cloud.online.net. 5 NS nsb.online.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0