Apex domains cannot have CNAME records.
Question and response
Question
dig filteredmx.net. NS
Answer
filteredmx.net. 5 NS ns2.kgix.com.
filteredmx.net. 5 NS ns3.kgix.com.
filteredmx.net. 5 NS ns1.kgix.com.
Authority
The response has no authority records.
Additional
ns1.kgix.com. 4 A 50.115.16.252
ns2.kgix.com. 4 A 162.159.24.207
ns3.kgix.com. 4 A 162.159.25.154
ns2.kgix.com. 4 AAAA 2400:cb00:2049:1:0:0:a29f:18cf
ns3.kgix.com. 4 AAAA 2400:cb00:2049:1:0:0:a29f:199a
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0