Apex domains cannot have CNAME records.
Question and response
Question
dig ALTO.FR. NS
Answer
ALTO.FR. 5 NS NS.ALTO.CH.
ALTO.FR. 5 NS NS.ALTO.FR.
ALTO.FR. 5 NS NS.ALTO.ORG.
Authority
The response has no authority records.
Additional
ns.alto.ch. 5 A 62.23.83.65
ns.alto.fr. 5 A 212.83.151.136
ns.alto.org. 5 A 212.83.151.135
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0