mail-out.cgp.vtr.net has no NS records.
NS records for this zone are defined at cgp.vtr.net.
NS records for this zone are defined at cgp.vtr.net.
Question and response
Question
dig mail-out.cgp.vtr.net. NS
Answer
The response has no answer records.
Authority
cgp.vtr.net. 300 SOA ns00.vtr.net. hostmaster.vtr.net. 2011101800 10800 3600 604800 38400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0