Apex domains cannot have CNAME records.
Question and response
Question
dig boostmobile.com. NS
Answer
boostmobile.com. 2 NS ns-1428.awsdns-50.org.
boostmobile.com. 2 NS ns-613.awsdns-12.net.
boostmobile.com. 2 NS ns-13.awsdns-01.com.
boostmobile.com. 2 NS ns-2009.awsdns-59.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0