mailb2b.tigo.com.co has no NS records.
NS records for this zone are defined at tigo.com.co.
NS records for this zone are defined at tigo.com.co.
Question and response
Question
dig mailb2b.tigo.com.co. NS
Answer
The response has no answer records.
Authority
tigo.com.co. 300 SOA lauta.une.net.co. root.une.net.co. 2026022701 2160 3600 86400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0