Apex domains cannot have CNAME records.
Question and response
Question
dig zctracker.com. NS
Answer
zctracker.com. 5 NS pdns90.ultradns.net.
zctracker.com. 5 NS ns1.zohocorp.com.
zctracker.com. 5 NS pdns90.ultradns.biz.
zctracker.com. 5 NS ns21.zns-53.net.
zctracker.com. 5 NS ns11.zns-53.com.
zctracker.com. 5 NS ns31.zns-53.com.
zctracker.com. 5 NS ns41.zns-53.net.
zctracker.com. 5 NS pdns90.ultradns.com.
Authority
The response has no authority records.
Additional
ns11.zns-53.com. 1 A 136.143.172.88
ns21.zns-53.net. 1 A 136.143.173.99
ns31.zns-53.com. 1 A 169.148.151.88
ns41.zns-53.net. 1 A 169.148.152.99
pdns90.ultradns.biz. 1 A 156.154.66.90
pdns90.ultradns.net. 1 A 156.154.65.90
ns11.zns-53.com. 1 AAAA 2602:801:c00a:0:0:0:0:88
ns21.zns-53.net. 1 AAAA 2602:801:c00b:0:0:0:0:99
ns31.zns-53.com. 1 AAAA 2602:801:c00c:0:0:0:0:88
ns41.zns-53.net. 1 AAAA 2602:801:c00c:0:0:0:0:99
pdns90.ultradns.biz. 1 AAAA 2610:a1:1015:0:0:0:0:7e
pdns90.ultradns.net. 1 AAAA 2610:a1:1014:0:0:0:0:7e
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0