Apex domains cannot have CNAME records.
Question and response
Question
dig orange.cm. NS
Answer
orange.cm. 4 NS douala0.orange.cm.
orange.cm. 4 NS yaounde0.orange.cm.
orange.cm. 4 NS garoua0.orange.cm.
Authority
The response has no authority records.
Additional
douala0.orange.cm. 4 A 41.202.217.13
garoua0.orange.cm. 4 A 102.244.72.5
yaounde0.orange.cm. 4 A 41.202.217.135
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0