Apex domains cannot have CNAME records.
Question and response
Question
dig cwbsa.com. NS
Answer
cwbsa.com. 5 NS ns-490.awsdns-61.com.
cwbsa.com. 5 NS ns-575.awsdns-07.net.
cwbsa.com. 5 NS ns-827.awsdns-39.net.
cwbsa.com. 5 NS ns-1950.awsdns-51.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0