Apex domains cannot have CNAME records.
Question and response
Question
dig htdgc.org. NS
Answer
htdgc.org. 5 NS ns-442.awsdns-55.com.
htdgc.org. 5 NS ns-1784.awsdns-31.co.uk.
htdgc.org. 5 NS ns-25.awsdns-03.com.
htdgc.org. 5 NS ns-749.awsdns-29.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0