Apex domains cannot have CNAME records.
Question and response
Question
dig infra.edpnet.net. NS
Answer
infra.edpnet.net. 5 NS ns2.edpnet.net.
infra.edpnet.net. 5 NS ns1.edpnet.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0