Apex domains cannot have CNAME records.
Question and response
Question
dig server.fido.net. NS
Answer
server.fido.net. 5 NS ns4.server.fido.net.
server.fido.net. 5 NS ns1.server.fido.net.
server.fido.net. 5 NS ns0.server.fido.net.
server.fido.net. 5 NS ns2.server.fido.net.
Authority
The response has no authority records.
Additional
ns0.server.fido.net. 5 A 192.88.83.53
ns1.server.fido.net. 5 A 84.246.192.54
ns2.server.fido.net. 5 A 194.70.36.53
ns4.server.fido.net. 5 A 192.88.83.53
ns0.server.fido.net. 5 AAAA 2a01:2c0:23db:0:0:0:0:53
ns1.server.fido.net. 5 AAAA 2a01:2c0:a:0:0:0:1:53
ns2.server.fido.net. 5 AAAA 2a01:2c0:a:0:0:0:2:53
ns4.server.fido.net. 5 AAAA 2a01:2c0:23db:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0