Apex domains cannot have CNAME records.
Question and response
Question
dig fb-t-msedge.net. NS
Answer
fb-t-msedge.net. 5 NS ns1.fb-t-msedge.net.
fb-t-msedge.net. 5 NS ns2.fb-t-msedge.net.
fb-t-msedge.net. 5 NS ns3.fb-t-msedge.net.
fb-t-msedge.net. 5 NS ns4.fb-t-msedge.net.
Authority
The response has no authority records.
Additional
ns1.fb-t-msedge.net. 5 A 13.107.253.1
ns2.fb-t-msedge.net. 5 A 13.107.253.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0