Apex domains cannot have CNAME records.
Question and response
Question
dig manageengine.com. NS
Answer
manageengine.com. 3 NS NS1.ZOHOCORP.COM.
manageengine.com. 3 NS PDNS90.ULTRADNS.COM.
manageengine.com. 3 NS ns41.zns-53.net.
manageengine.com. 3 NS ns31.zns-53.com.
manageengine.com. 3 NS ns21.zns-53.net.
manageengine.com. 3 NS PDNS90.ULTRADNS.NET.
manageengine.com. 3 NS ns11.zns-53.com.
manageengine.com. 3 NS PDNS90.ULTRADNS.BIZ.
Authority
The response has no authority records.
Additional
ns1.zohocorp.com. 3 A 156.154.67.90
ns11.zns-53.com. 3 A 136.143.172.88
ns21.zns-53.net. 3 A 136.143.173.99
ns31.zns-53.com. 3 A 169.148.151.88
ns41.zns-53.net. 3 A 169.148.152.99
ns1.zohocorp.com. 3 AAAA 2001:502:4612:0:0:0:0:7e
ns11.zns-53.com. 3 AAAA 2602:801:c00a:0:0:0:0:88
ns21.zns-53.net. 3 AAAA 2602:801:c00b:0:0:0:0:99
ns31.zns-53.com. 3 AAAA 2602:801:c00c:0:0:0:0:88
ns41.zns-53.net. 3 AAAA 2602:801:c00c:0:0:0:0:99
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0