Apex domains cannot have CNAME records.
Question and response
Question
dig prod.coredial.com. NS
Answer
prod.coredial.com. 5 NS ns-1470.awsdns-55.org.
prod.coredial.com. 5 NS ns-322.awsdns-40.com.
prod.coredial.com. 5 NS ns-624.awsdns-14.net.
prod.coredial.com. 5 NS ns-1760.awsdns-28.co.uk.
Authority
The response has no authority records.
Additional
ns-322.awsdns-40.com. 4 A 205.251.193.66
ns-624.awsdns-14.net. 4 A 205.251.194.112
ns-1470.awsdns-55.org. 4 A 205.251.197.190
ns-1760.awsdns-28.co.uk. 4 A 205.251.198.224
ns-322.awsdns-40.com. 4 AAAA 2600:9000:5301:4200:0:0:0:1
ns-624.awsdns-14.net. 4 AAAA 2600:9000:5302:7000:0:0:0:1
ns-1470.awsdns-55.org. 4 AAAA 2600:9000:5305:be00:0:0:0:1
ns-1760.awsdns-28.co.uk. 4 AAAA 2600:9000:5306:e000:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0