Apex domains cannot have CNAME records.
Question and response
Question
dig sunplusit.com. NS
Answer
sunplusit.com. 5 NS dns2.sunplusit.com.
sunplusit.com. 5 NS dns.sunplusit.com.
Authority
The response has no authority records.
Additional
dns.sunplusit.com. 5 A 52.196.157.30
dns2.sunplusit.com. 5 A 60.248.186.158
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0