Apex domains cannot have CNAME records.
Question and response
Question
dig replibit.com. NS
Answer
replibit.com. 5 NS ns5.efscloud.net.
replibit.com. 5 NS ns2.efscloud.net.
replibit.com. 5 NS ns3.efscloud.net.
replibit.com. 5 NS ns4.efscloud.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0