Apex domains cannot have CNAME records.
Question and response
Question
dig synchronoss.com. NS
Answer
synchronoss.com. 5 NS ns2.synchronoss.com.
synchronoss.com. 5 NS ns1.synchronoss.com.
synchronoss.com. 5 NS ns3.synchronoss.com.
Authority
The response has no authority records.
Additional
ns1.synchronoss.com. 5 A 74.116.108.190
ns2.synchronoss.com. 5 A 74.116.109.190
ns3.synchronoss.com. 5 A 3.218.123.96
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0