Apex domains cannot have CNAME records.
Question and response
Question
dig network-box.com. NS
Answer
network-box.com. 5 NS dns4.network-box.com.
network-box.com. 5 NS dns3.network-box.com.
network-box.com. 5 NS dns1.network-box.com.
network-box.com. 5 NS dns2.network-box.com.
Authority
The response has no authority records.
Additional
dns1.network-box.com. 5 A 202.52.43.183
dns2.network-box.com. 5 A 52.28.208.16
dns3.network-box.com. 5 A 14.198.177.40
dns4.network-box.com. 5 A 52.3.204.139
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0