_spf.poa.svr4u.net has no NS records.
NS records for this zone are defined at poa.svr4u.net.
NS records for this zone are defined at poa.svr4u.net.
Question and response
Question
dig _spf.poa.svr4u.net. NS
Answer
The response has no answer records.
Authority
poa.svr4u.net. 1800 SOA ns.namedserver.net. root.namedserver.net. 2763632194 10800 1800 259200 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0