Apex domains cannot have CNAME records.
Question and response
Question
dig zohodesk.com. NS
Answer
zohodesk.com. 1 NS ns41.zns-53.net.
zohodesk.com. 1 NS ns21.zns-53.net.
zohodesk.com. 1 NS ns11.zns-53.com.
zohodesk.com. 1 NS ns1.zohocorp.com.
zohodesk.com. 1 NS ns31.zns-53.com.
zohodesk.com. 1 NS pdns90.ultradns.biz.
zohodesk.com. 1 NS pdns90.ultradns.com.
zohodesk.com. 1 NS pdns90.ultradns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0