Apex domains cannot have CNAME records.
Question and response
Question
dig mailernet.work. NS
Answer
mailernet.work. 5 NS ns2.mailernet.work.
mailernet.work. 5 NS ns1.mailernet.work.
Authority
The response has no authority records.
Additional
ns1.mailernet.work. 5 A 172.105.20.117
ns2.mailernet.work. 5 A 172.105.13.24
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0