Apex domains cannot have CNAME records.
Question and response
Question
dig broadridge.com. NS
Answer
broadridge.com. 5 NS ns89.ultradns2.com.
broadridge.com. 5 NS edns1.ultradns.biz.
broadridge.com. 5 NS edns1.ultradns.net.
broadridge.com. 5 NS edns1.ultradns.com.
broadridge.com. 5 NS ns89.ultradns2.org.
broadridge.com. 5 NS edns1.ultradns.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0