Apex domains cannot have CNAME records.
Question and response
Question
dig insurvey.com. NS
Answer
insurvey.com. 5 NS ns10.digicertdns.com.
insurvey.com. 5 NS ns12.digicertdns.com.
insurvey.com. 5 NS ns11.digicertdns.com.
insurvey.com. 5 NS ns13.digicertdns.net.
insurvey.com. 5 NS ns14.digicertdns.net.
insurvey.com. 5 NS ns15.digicertdns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0