Apex domains cannot have CNAME records.
Question and response
Question
dig peekboo.com. NS
Answer
peekboo.com. 3 NS ns-301.awsdns-37.com.
peekboo.com. 3 NS ns-1239.awsdns-26.org.
peekboo.com. 3 NS ns-1050.awsdns-03.org.
peekboo.com. 3 NS ns-1656.awsdns-15.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0