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