Apex domains cannot have CNAME records.
Question and response
Question
dig groupgti.com. NS
Answer
groupgti.com. 5 NS ns-1523.awsdns-62.org.
groupgti.com. 5 NS ns-981.awsdns-58.net.
groupgti.com. 5 NS ns-298.awsdns-37.com.
groupgti.com. 5 NS ns-1739.awsdns-25.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0