Apex domains cannot have CNAME records.
Question and response
Question
dig fiserv.com. NS
Answer
fiserv.com. 5 NS ns1.p201.dns.oraclecloud.net.
fiserv.com. 5 NS dns2.p07.nsone.net.
fiserv.com. 5 NS ns2.p201.dns.oraclecloud.net.
fiserv.com. 5 NS dns4.p07.nsone.net.
Authority
The response has no authority records.
Additional
dns2.p07.nsone.net. 3 A 198.51.45.7
dns4.p07.nsone.net. 3 A 198.51.45.71
dns2.p07.nsone.net. 3 AAAA 2a00:edc0:6259:7:7:0:0:2
dns4.p07.nsone.net. 3 AAAA 2a00:edc0:6259:7:7:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0