ns2.u-servers.net has no NS records.
NS records for this zone are defined at u-servers.net.
NS records for this zone are defined at u-servers.net.
Question and response
Question
dig ns2.u-servers.net. NS
Answer
The response has no answer records.
Authority
u-servers.net. 300 SOA ns1.uni-one.net. hostmaster.uni-one.net. 2020112704 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0