spf.trustico.com has no NS records.
NS records for this zone are defined at trustico.com.
NS records for this zone are defined at trustico.com.
Question and response
Question
dig spf.trustico.com. NS
Answer
The response has no answer records.
Authority
trustico.com. 180 SOA ns11.constellix.com. dns.constellix.com. 2015010352 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0