_spf.etrn.com has no NS records.
NS records for this zone are defined at etrn.com.
NS records for this zone are defined at etrn.com.
Question and response
Question
dig _spf.etrn.com. NS
Answer
The response has no answer records.
Authority
etrn.com. 2560 SOA ns1.chi1.etrn.com. hostmaster.etrn.com. 1771702010 16384 2048 1048576 2560
Additional
The response has no additional records.