correo2.tigo.bo has no NS records.
NS records for this zone are defined at tigo.bo.
NS records for this zone are defined at tigo.bo.
Question and response
Question
dig correo2.tigo.bo. NS
Answer
The response has no answer records.
Authority
tigo.bo. 900 SOA dns1.wimaxtigo.bo. please_set_email.absolutely.nowhere.tigo.bo. 81 10800 3600 2419200 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0