spf.mittum.com has no NS records.
NS records for this zone are defined at mittum.com.
NS records for this zone are defined at mittum.com.
Question and response
Question
dig spf.mittum.com. NS
Answer
The response has no answer records.
Authority
mittum.com. 3600 SOA dns3.elogia.net. hostmaster.elogia.net. 2017064104 21600 3600 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0