_spf4.fiserv.com has no NS records.
NS records for this zone are defined at fiserv.com.
NS records for this zone are defined at fiserv.com.
Question and response
Question
dig _spf4.fiserv.com. NS
Answer
The response has no answer records.
Authority
fiserv.com. 300 SOA dns2.p07.nsone.net. domainadmin.firstdata.com. 763100884 1200 180 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0