Apex domains cannot have CNAME records.
Question and response
Question
dig volia.net. NS
Answer
volia.net. 5 NS ns3.voliacable.com.
volia.net. 5 NS ns3.volia.net.
volia.net. 5 NS ns1.volia.net.
volia.net. 5 NS ns2.volia.net.
volia.net. 5 NS ns2.voliacable.com.
volia.net. 5 NS ns1.voliacable.com.
Authority
The response has no authority records.
Additional
ns1.volia.net. 5 A 82.144.192.40
ns2.volia.net. 5 A 82.144.192.50
ns3.volia.net. 5 A 20.71.175.249
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0