Apex domains cannot have CNAME records.
Question and response
Question
dig upmc.FR. NS
Answer
upmc.FR. 5 NS ganesh.upmc.FR.
upmc.FR. 5 NS ns0.sorbonne-universite.FR.
upmc.FR. 5 NS shiva.jussieu.FR.
upmc.FR. 5 NS ns1.sorbonne-universite.FR.
upmc.FR. 5 NS soleil.uvsq.FR.
Authority
The response has no authority records.
Additional
shiva.jussieu.fr. 5 A 134.157.0.129
ganesh.upmc.fr. 5 A 134.157.192.1
soleil.uvsq.fr. 5 A 193.51.24.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0