Apex domains cannot have CNAME records.
Question and response
Question
dig onlinefreeebooks.com. NS
Answer
onlinefreeebooks.com. 5 NS ns2kry.name.com.
onlinefreeebooks.com. 5 NS ns1ntw.name.com.
onlinefreeebooks.com. 5 NS ns4ksy.name.com.
onlinefreeebooks.com. 5 NS ns3fgh.name.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0