mx20.013net.net has no NS records.
NS records for this zone are defined at 013net.net.
NS records for this zone are defined at 013net.net.
Question and response
Question
dig mx20.013net.net. NS
Answer
The response has no answer records.
Authority
013net.net. 86400 SOA dns.netvision.net.il. hostmaster.netvision.net.il. 2025090901 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0