_spf.megamail.nl has no NS records.
NS records for this zone are defined at megamail.nl.
NS records for this zone are defined at megamail.nl.
Question and response
Question
dig _spf.megamail.nl. NS
Answer
The response has no answer records.
Authority
megamail.nl. 900 SOA ns1.hix.nl. postmaster.megamail.nl. 2013021200 10800 3600 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0