mns.yi.org has no NS records.
NS records for this zone are defined at yi.org.
NS records for this zone are defined at yi.org.
Question and response
Question
dig free.hf4l.com. NS
Answer
The response has no answer records.
Authority
hf4l.com. 3601 SOA dns1.registrar-servers.com. hostmaster.registrar-servers.com. 1770245385 43200 3600 604800 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0