Apex domains cannot have CNAME records.
Question and response
Question
dig dooray.com. NS
Answer
dooray.com. 5 NS a12-65.akam.net.
dooray.com. 5 NS a3-66.akam.net.
dooray.com. 5 NS a1-57.akam.net.
dooray.com. 5 NS a4-67.akam.net.
dooray.com. 5 NS a8-64.akam.net.
dooray.com. 5 NS a11-64.akam.net.
Authority
The response has no authority records.
Additional
a4-67.akam.net. 1 A 72.246.46.67
a11-64.akam.net. 1 A 84.53.139.64
a4-67.akam.net. 1 AAAA 2600:1480:9000:0:0:0:0:43
a11-64.akam.net. 1 AAAA 2600:1480:1:0:0:0:0:40
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0