Apex domains cannot have CNAME records.
Question and response
Question
dig bom1.prodgdc.com. NS
Answer
bom1.prodgdc.com. 5 NS ns-297.awsdns-37.com.
bom1.prodgdc.com. 5 NS ns-1552.awsdns-02.co.uk.
bom1.prodgdc.com. 5 NS ns-1040.awsdns-02.org.
bom1.prodgdc.com. 5 NS ns-770.awsdns-32.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0