Apex domains cannot have CNAME records.
Question and response
Question
dig cpanel16.hosting.astutium.com. NS
Answer
cpanel16.hosting.astutium.com. 5 NS ns3.this-dns.net.
cpanel16.hosting.astutium.com. 5 NS ns2.this-dns.net.
cpanel16.hosting.astutium.com. 5 NS ns1.this-dns.net.
cpanel16.hosting.astutium.com. 5 NS ns4.this-dns.net.
Authority
The response has no authority records.
Additional
ns1.this-dns.net. 5 A 80.76.218.199
ns2.this-dns.net. 5 A 95.128.49.99
ns3.this-dns.net. 5 A 80.76.218.200
ns4.this-dns.net. 5 A 95.128.49.100
ns3.this-dns.net. 5 AAAA 2001:4bf0:1:0:101:0:1:10
ns4.this-dns.net. 5 AAAA 2001:4bf0:1:0:101:0:2:10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0