Apex domains cannot have CNAME records.
Question and response
Question
dig namginc.com. NS
Answer
namginc.com. 5 NS ns-707.awsdns-24.net.
namginc.com. 5 NS ns-300.awsdns-37.com.
namginc.com. 5 NS ns-2002.awsdns-58.co.uk.
namginc.com. 5 NS ns-1072.awsdns-06.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0