Apex domains cannot have CNAME records.
Question and response
Question
dig zohomail360.com. NS
Answer
zohomail360.com. 5 NS dns1.p03.nsone.net.
zohomail360.com. 5 NS dns2.p03.nsone.net.
zohomail360.com. 5 NS pdns90.ultradns.org.
zohomail360.com. 5 NS dns4.p03.nsone.net.
zohomail360.com. 5 NS pdns90.ultradns.com.
zohomail360.com. 5 NS dns3.p03.nsone.net.
zohomail360.com. 5 NS pdns90.ultradns.net.
zohomail360.com. 5 NS ns1.zohocorp.com.
zohomail360.com. 5 NS pdns90.ultradns.biz.
Authority
The response has no authority records.
Additional
ns1.zohocorp.com. 5 A 156.154.67.90
ns1.zohocorp.com. 5 AAAA 2001:502:4612:0:0:0:0:7e
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0