Apex domains cannot have CNAME records.
Question and response
Question
dig syd1.prodgdc.com. NS
Answer
syd1.prodgdc.com. 5 NS ns-1881.awsdns-43.co.uk.
syd1.prodgdc.com. 5 NS ns-809.awsdns-37.net.
syd1.prodgdc.com. 5 NS ns-209.awsdns-26.com.
syd1.prodgdc.com. 5 NS ns-1416.awsdns-49.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0