Apex domains cannot have CNAME records.
Question and response
Question
dig fortiphish.com. NS
Answer
fortiphish.com. 5 NS ns-56.awsdns-07.com.
fortiphish.com. 5 NS ns-1230.awsdns-25.org.
fortiphish.com. 5 NS ns-590.awsdns-09.net.
fortiphish.com. 5 NS ns-1831.awsdns-36.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0