filter.onlinespamfilter.com has no NS records.
NS records for this zone are defined at onlinespamfilter.com.
NS records for this zone are defined at onlinespamfilter.com.
Question and response
Question
dig filter.onlinespamfilter.com. NS
Answer
The response has no answer records.
Authority
onlinespamfilter.com. 300 SOA ns-cloud-b1.googledomains.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0