spf01.t-com.ne.jp has no NS records.
NS records for this zone are defined at t-com.ne.jp.
NS records for this zone are defined at t-com.ne.jp.
Question and response
Question
dig spf01.t-com.ne.jp. NS
Answer
The response has no answer records.
Authority
t-com.ne.jp. 300 SOA dns0.tokai.or.jp. postmaster.tokai.or.jp. 202601002 86400 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0