mail.claro.com.co has no NS records.
NS records for this zone are defined at claro.com.co.
NS records for this zone are defined at claro.com.co.
Question and response
Question
dig mail.claro.com.co. NS
Answer
The response has no answer records.
Authority
claro.com.co. 3600 SOA w2kbogccdnsep.comcel.com.co. nocdatos.comcel.com.co. 2018024172 3600 600 1296000 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0