Apex domains cannot have CNAME records.
Question and response
Question
dig exact.com. NS
Answer
exact.com. 5 NS ns-1451.awsdns-53.org.
exact.com. 5 NS ns-735.awsdns-27.net.
exact.com. 5 NS ns-54.awsdns-06.com.
exact.com. 5 NS ns-1685.awsdns-18.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0