Apex domains cannot have CNAME records.
Question and response
Question
dig ivpc.prod.cloud.synchronoss.net. NS
Answer
ivpc.prod.cloud.synchronoss.net. 5 NS ns-505.awsdns-63.com.
ivpc.prod.cloud.synchronoss.net. 5 NS ns-1175.awsdns-18.org.
ivpc.prod.cloud.synchronoss.net. 5 NS ns-600.awsdns-11.net.
ivpc.prod.cloud.synchronoss.net. 5 NS ns-1809.awsdns-34.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0