Apex domains cannot have CNAME records.
Question and response
Question
dig prtimes.jp. NS
Answer
prtimes.jp. 5 NS ns-1229.awsdns-25.org.
prtimes.jp. 5 NS ns-169.awsdns-21.com.
prtimes.jp. 5 NS ns-734.awsdns-27.net.
prtimes.jp. 5 NS ns-1545.awsdns-01.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0