Apex domains cannot have CNAME records.
Question and response
Question
dig saiglobal.com. NS
Answer
saiglobal.com. 4 NS ns-923.awsdns-51.net.
saiglobal.com. 4 NS ns-453.awsdns-56.com.
saiglobal.com. 4 NS ns-1936.awsdns-50.co.uk.
saiglobal.com. 4 NS ns-1145.awsdns-15.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0