dns2.servidoresdns.net has no NS records.
NS records for this zone are defined at servidoresdns.net.
NS records for this zone are defined at servidoresdns.net.
Question and response
Question
dig dns2.servidoresdns.net. NS
Answer
The response has no answer records.
Authority
servidoresdns.net. 3600 SOA atlante.servidoresdns.net. hostmaster.arsys.es. 2005152369 86400 7200 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0