fbl.sendclean.com has no NS records.
NS records for this zone are defined at sendclean.com.
NS records for this zone are defined at sendclean.com.
Question and response
Question
dig fbl.sendclean.com. NS
Answer
The response has no answer records.
Authority
sendclean.com. 300 SOA ns-cloud-c1.googledomains.com. cloud-dns-hostmaster.google.com. 115 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0