ns2.unit-is.com has no NS records.
NS records for this zone are defined at unit-is.com.
NS records for this zone are defined at unit-is.com.
Question and response
Question
dig ns2.unit-is.com. NS
Answer
The response has no answer records.
Authority
unit-is.com. 3600 SOA h102.unit-is.com. admin.unit-is.com. 2017013404 10800 3600 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0