mail.rg.net has no NS records.
NS records for this zone are defined at rg.net.
NS records for this zone are defined at rg.net.
Question and response
Question
dig mail.rg.net. NS
Answer
The response has no answer records.
Authority
rg.net. 14400 SOA rip.psg.com. hostmaster.psg.com. 1772565969 86400 3600 2592000 14400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0