mx.uhserver.com has no NS records.
NS records for this zone are defined at uhserver.com.
NS records for this zone are defined at uhserver.com.
Question and response
Question
dig mx.uhserver.com. NS
Answer
The response has no answer records.
Authority
uhserver.com. 300 SOA ns1.host.uol.com.br. admin.uolhost.com.br. 2025093001 43200 3600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0