Apex domains cannot have CNAME records.
Question and response
Question
dig workfront.com. NS
Answer
workfront.com. 5 NS ns-1919.awsdns-47.co.uk.
workfront.com. 5 NS ns-776.awsdns-33.net.
workfront.com. 5 NS ns-201.awsdns-25.com.
workfront.com. 5 NS ns-1495.awsdns-58.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0