Apex domains cannot have CNAME records.
Question and response
Question
dig gigya.com. NS
Answer
gigya.com. 5 NS ns-1877.awsdns-42.co.uk.
gigya.com. 5 NS ns-1099.awsdns-09.org.
gigya.com. 5 NS ns-499.awsdns-62.com.
gigya.com. 5 NS ns-864.awsdns-44.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0