spf2.posti.com has no NS records.
NS records for this zone are defined at posti.com.
NS records for this zone are defined at posti.com.
Question and response
Question
dig spf2.posti.com. NS
Answer
The response has no answer records.
Authority
posti.com. 900 SOA ns15.posti.fi. hostmaster.posti.com. 2015102130 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0