Apex domains cannot have CNAME records.
Question and response
Question
dig masaru471002.com. NS
Answer
masaru471002.com. 5 NS ns-322.awsdns-40.com.
masaru471002.com. 5 NS ns-899.awsdns-48.net.
masaru471002.com. 5 NS ns-1381.awsdns-44.org.
masaru471002.com. 5 NS ns-1973.awsdns-54.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0