spf.ti.com has no NS records.
NS records for this zone are defined at ti.com.
NS records for this zone are defined at ti.com.
Question and response
Question
dig spf.ti.com. NS
Answer
The response has no answer records.
Authority
ti.com. 30 SOA oqdibfd.itg.ti.com. hostmaster.ti.com. 2013108351 900 300 2419200 30
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0